The Ambassadors of Death


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The Ambassadors of Death

Serial Code


First Transmitted

21 March 1970

Final Ratings






The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
The Ambassadors Of Death
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Regular Cast

Jon Pertwee (Doctor Who) Caroline John (Liz Shaw)

Guest Cast

Nicholas Courtney (Brigadier Lethbridge-Stewart), Ronald Allen (Ralph Cornish), Robert Cawdron (Taltalian) [1-2, 4], John Abineri (Carrington / General Carrington), Ric Felgate (Van Lyden) [1-3, 6], Michael Wisher (John Wakefield) [1-2, 7], Cheryl Molineaux (Miss Rutherford) [1-2], Ray Armstrong (Grey) [1-2], Robert Robertson (Collinson) [1-2], Dallas Cavell (Quinlan) [2-5], Bernard Martin [2], Joanna Ross [5-7], Carl Conway [5-6] (Control Room Assistant), Juan Moreno (Dobson) [2], James Haswell (Corporal Champion) [2], Derek Ware (UNIT Sergeant) [2], William Dysart (Reegan) [3-7], Cyril Shaps (Lennox) [3-5], Gordon Sterne (Heldorf) [3], Steve Peters [3-5, 7], Neville Simons [3-5, 7], Ric Felgate [4-5, 7] (Astronauts), Max Faulkner (UNIT Soldier) [4], John Lord (Masters) [4], Tony Harwood (Flynn) [5], John Levene (Sergeant Benton) [5, 7], James Clayton (Private Parker) [5], Roy Scammell (Technician) [5], Peter Noel Cook (Alien Space Captain) [6-7], Peter Halliday (Aliens’ Voices) [6-7], Steve Peters (Lefee) [6], Neville Simons (Michaels) [6], Geoffrey Beevers (Private Johnson) [7].


Written by David Whitaker
Directed by Michael Ferguson
Produced by Barry Letts


1 “Episode One” 24:33 21 March 1970 7.1m
2 “Episode Two” 24:39 28 March 1970 7.6m
3 “Episode Three” 24:38 4 April 1970 8.0m
4 “Episode Four” 24:37 11 April 1970 9.3m
5 “Episode Five” 24:17 18 April 1970 7.1m
6 “Episode Six” 24:31 25 April 1970 6.9m
7 “Episode Seven” 24:32 2 May 1970 5.4m


When all communication is lost from Mars Probe 7 shortly after it leaves Mars and begins its trip back to Earth, a second craft is launched to investigate. As Recovery 7 docks in space, it too loses all communication…

The Doctor and UNIT are given the task of investigating the mystery, as Recovery 7 returns to Earth. It appears that no one can be trusted, as the space capsule is hijacked from its UNIT convoy with military precise. What has happened to the missing astronauts? Could this be a secret invasion from Mars, or is the enemy much closer to home?

As The Doctor plans a daring space mission of his own, his assistant Liz Shaw goes missing. Who is working against UNIT in order to bring mankind into conflict with an alien race…?


An astronaut is bearing down on Mars Probe 7. There has been no contact between the probe and Earth for seven months when it took off from Mars. The Brigadier, who is overlooking the proceedings in the Space Centre, asks Professor Cornish, who is running the recovery mission, if he considers them to be dead. Cornish says he suspects so. The whole recovery mission is being televised live.

The Doctor is trying to reactivate the Time Vector Generator using his TARDIS control. He inadvertently sends Liz fifteen seconds into the future before doing so to himself — much to her confusion. The Doctor notices the Brigadieron television. He is still bitter about the Brigadier’s decision to destroy the Silurians. The recovery vessel is about to link up with the probe.

The Brigadier asks the astronaut if he is sure the probe is Mars Probe 7. He says it is. He tries for radio communication one last time and then begins the process of linking up.

The Doctor watches, enthralled.

The astronaut activates the airlock. The air holds. He goes to open the hatch and hears something on the other side. He thinks he hears the hatch in the probe open. He opens his own hatch.

Communication is lost in the Space Centre. All they hear is a shrill noise that hurts the ears of everyone listening. When it is done their is no contact.

Back at UNIT headquarters, The Doctor recognises the sound but can’t place from where, which frustrates him. He and Liz set off for the Space Centre.

Cornish is told there are no issues with any of the equipment at the Space Centre, so it must be an issue on the vessels. One of the other doctors, by the name of Taltalian, is being interviewed but gets frustrated with the journalist and walks off.

The Doctor drives into the Space Centre directly after another vehicle, much to the concern of the guards.

The probe is holding its position. One of the scientists wonders if it was an excess of electricity built up in the probe that may have fried the communications but not killed the astronauts. The Doctor arrives, pursued by soldiers that are called off by the Brigadier. The Doctor says that the sound is a message. Cornish is dismissive of the Doctor, but the sound returns. The Doctor identifies it as a series of high frequency accelerated impulses. He demands unlimited computer time and multiple copies of the recording so as to analyse it. Cornish’s back is still up. The Doctor becomes more consolatory to him, and he calms down. The sound appears again — but this time it is slightly different. The Doctor states it is a reply from Earth. He sets about coordinating a worldwide triangulation in expectation of a replay.

The broadcasters suggest that the noise is some kind of distress signal.

The Doctor is setting up the triangulation. Taltalian has set up another recovery probe that won’t be ready for another ten days. Cornish is not happy with that and orders him to speed up or find another capsule from another country. Taltalian says there is no capsule ready in the world. The noise is replayed, and the Doctor sets about collating the data. Liz receives some data from France which confirms that the signal is coming from London. The Brigadier gets UNIT to do a local triangulation, which places it as emanating from an abandoned warehouse seven miles from where they are.

Two men are sending a message from the warehouse. The UNIT forces arrive outside the warehouse.

The two men stop the signal and wait for a response. They know they will be being monitored but hope they won’t be tracked. An associate of theirs called the Sergeant enters and says that UNIT forces have arrived. He is ordered to stall them but only kill if necessary.

A group of people, led by the Sergeant, hide from UNIT. The Sergeant fires his gun.

The two men send the signal again, confident that the Sergeant will hold them off.

The Sergeant kills one of the UNIT soldiers, and a fire fight ensues. Many are killed as some of the Sergeant’s associates join in. It soon becomes a hand to hand battle. The Brigadier stops the Sergeant from escaping. They face each other, both pointing their guns at one another. A UNIT soldier approaches from behind the Sergeant and swings a heavy metal implement attached to the ceiling. The Sergeant dodges it, and the Brigadier is disarmed. The Sergeant has a clean shot of the Brigadier. Instead, he drops his gun and is led away.

The two men trigger the self destruct function on the machine they have been using. The men go through the window, but not before they draw the Brigadier in by firing their gun. As the Brigadier enters, the communication device explodes.

The Doctor complains to Cornish that Taltalian is refusing him use of his computers. Cornish contacts Taltalian and orders him to comply with The Doctor. Cornish is told by Athens that a solar flare is heading directly for where the probe is in orbit. Their controls are locked on manual, and there is nothing that can be done. He contacts them, imploring them to unlock the manual setting.

On Mars Probe 7, Cornish’s pleas echo round an empty cockpit.

The Doctor and Liz enter the computer suite only for Taltalian to emerge from behind the door and pull a gun on them.


Taltalian demands the tape. The Doctor asks if he understood the message, and Taltalian says he did. The Doctor holds the tape out to Taltalian — only to make it disappear. Taltalian searches The Doctor for it, but is interrupted by the entrance of the Brigadier. Panicked, Taltalian takes Liz hostage until he can escape. The Brigadier pursues. The Doctor makes the tape reappear and explains to Liz that he transmigrated it, but won’t explain how. The Doctor and Liz find the analogue to digital converter. The Brigadier returns and says that Taltalian escaped. The Brigadier tells The Doctor about what happened at the warehouse and says they have taken prisoners. The Doctor wishes to talk to them.

The Doctor and the Brigadier interrogate the Sergeant, but he won’t talk. The Brigadier asks him why he didn’t shoot him when he had the chance. The Doctor suggests he was ordered not to. The Brigadier tells The Doctor that they have no knowledge of the Sergeant — even the labels of his clothes have been removed. The Doctor realises that they are dealing with something larger than the Sergeant and goes to leave. Before he does, he asks the Sergeant nicely if there is anything he can get for him before shouting at him like an army officer: “Stand to attention when you speak to me, and call me ‘sir’!” The Sergeant springs to attention. The Doctor tells the Brigadier that the Sergeant is an army officerof some kind. A scientist comes to get The Doctor.

John Wakefield informs the public that the two capsules have separated, but there is still no communication from eitherof the vessels.

The Doctor and the Brigadier return to be told that the vessels are seven miles apart and expanding. The recovery shuttle is heading towards Earth and is eleven minutes from re-entry. They are all surprised when the shuttle starts its re-entryearly. The Doctor leaves to check on Liz. The Brigadier leaves to run a security report on the Sergeant.

Unbeknownst to the Brigadier, an anonymous figure disarms a UNIT soldier and frees the Sergeant.

Liz and another scientist called Dobson have found no pattern to the tape. The Doctor suggests there might be something wrong with the computer. Dobson is sceptical, saying that the computer is infallible. The Doctor gets Liz to ask the computer what two plus two is. The computer responds with five. The Doctor says that Taltalian has sabotaged the computer.

The recovery shuttle is ten seconds from control range. Contact is established between the shuttle and the Space Centre, but there is no response. The Brigadier is worried that the shuttle will burn up on re-entry. The Space Centre takes over control of the shuttle. Radar contact is made.

The broadcast tells the public that the capsule is on course to land somewhere in the South of England.

The Space Centre is tracking the capsule and controls its landing. Once it lands, the Brigadier and the Doctor congratulate Cornish.

The Doctor, the Brigadier and Cornish go out to the capsule. Cornish speaks to the astronauts through a communication device on the outside of the shuttle. There is no response. Unbeknownst by them, they are being watched by the men from the warehouse. Cornish wonders if the astronauts are unconscious and also tells The Doctor and the Brigadier that the mechanism is jammed or locked and that they can’t cut into the capsule as it would be dangerous for the astronauts. The Brigadier suggest they take the capsule back to the Space Centre. The Brigadier contacts UNIT headquarters and orders that the route is cleared between where the capsule landed and the Space Centre. He also asks for police outriders to accompany them. They load the capsule onto the back of a truck and head off. The Brigadier goes with the capsule in the truck, whilst The Doctor goes separately in Bessie.

The Brigadier sees a helicopter in pursuit of the truck. It hovers over the truck and drops smoke grenades, which disorientate the driver and the outriders. The truck is forced to stop. The helicopter lands. A firefight ensues between the UNIT soldiers and the men in the helicopter, who have alien weapons. Many UNIT soldiers are killed. One of the men takes off with the helicopter, whilst two others, the ones from the warehouse, steal the truck.

The Doctor comes across the truck, and blocks the way with Bessie. The two men ask him to move, but The Doctor takes on the role of a doddery old man whose car has stalled, asking for their help in moving the vehicle. The men get out and push Bessie to the side of the road. As they do, The Doctor activates an anti-thief device switch on the dashboard, which causes Bessie to become “magnetised” and leaves the men unable to remove their hands from the car. The Doctor steals the truck back.

The Brigadier is complaining to Cornish about the theft of the truck. He is flabbergasted to round the corner and see the recovery capsule being examined. The Doctor appears and explains what happened. He receives a phone call from Liz to say she has discovered the pattern. The Doctor leaves. Cornish continues connecting equipment to the capsule.

Liz shows The Doctor the pattern she discovered. It proves that Taltalian has some kind of prior information regarding the situation. The Doctor heads off, saying that he is going to go and talk to the “top man”. Once alone, Dobson rings someone and informs them that the code is close to being cracked.

The Doctor and the Brigadier explain to Sir James Quinlan, the Minister for Technology, everything that has happened and their theory that there is a mole. Sir James seems blasé and sends the two men away. The Doctor is cross, but the Brigadier shuts him up. When The Doctor and the Brigadier leave, he goes to his cupboard where Taltalian has been hidden.

There is no response from Recovery 7. Cornish is preparing the thermal lances when Liz starts picking up some static.

Sir James and Taltalian discuss how The Doctor is getting closer to their secret. Sir James say they are soon going to get a surprise.

A voice comes over the radio from the shuttle:; it is Van Lyden, asking for re-entry clearance. Cornish proudly tells Van Lyden that he and his fellow astronauts are back at the Space Centre, but Van Lyden replies “We are not cleared for re-entry.” The Doctor asks Van Lyden “What is the capital of Australia?” and “How many beans make five?”, only to receive the same phrase in reply each time. The Doctor tells Cornish’s workman to cut open the capsule.


The craft is opened and found to be empty, save for a tape recorder — which is not standard equipment, according to Cornish — with a recording of Van Lyden’s voice, which automatically activates in response to the radio; and a high amount of radiation.

|General Carrington has ensured the capsule’s crew — three spacesuited astronauts — are detained elsewhere, feeding them radiation to keep them alive. Carrington is introduced to The Doctor by Quinlan who explains that he is head of the newly formed Space Security Department and that his actions were to protect the astronauts as they had been infected with contagious radiation. Quinlan states that they did not want the public to become panic-stricken, so Carrington had been acting with authority in his actions. By the time Carrington takes The Doctor and his friends to meet the astronauts, the situation has changed again.

A criminal named Reegan has organised their abduction, killing the soldiers and scientists protecting them. Two of his henchmen are ordered to protect the astronauts, but the radiation they emit later kills them. Reegan, suited in protective clothes, disposes of their irradiated bodies in a Hertfordshire gravel pit, burying them under the rocks. He then returns to his laundry van. Covering his tracks with camouflage tactics, Reegan pushes a dashboard button that flips over the van’s number plate so it reads another registration. At the same time, the “Hayhoe Launderers Ltd” signage on the van changes to read “Silcock Bakeries”. Lateron, the worker manning the industrial shovel uncovers the bodies when sifting the gravel.

When The Doctor and Liz examine the situation, they work out that human tissue could not have withstood the degree of radiation emitted to the astronauts, who are still in orbit, meaning the three space suits contain alien beings instead. Reegan and his own scientist, Lennox, a disgraced Cambridge professor, are keeping the aliens alive, thinking the radiation needs to disperse, but they are weakening. Reegan enters their locked chamber to check up on one that collapses, but the alien recovers, thrusts him into a wall, and attempts to escape. Lennox flees, running up to find the laboratory exit locked, nearly getting him killed by the advancing alien. It runs out of strength again and falls down the stairs before laying a hand on him. Reegan recovers from the attack, disregarding Lennox’s anger about locking the door. They realise the aliens need radiation to survive and begin dosing them with isotopes.

In order to aid Lennox in maintaining the alien beings While they are incarcerated, Reegan lures Liz and the Doctor into the open by issuing a false announcement that the Brigadier wants them to examine the bodies of the radiation victims now uncovered in the gravel pit. The Doctor chooses not to go, wanting to ready Recovery 7 for another flight into space rather than wait for Recovery 8, as its radiation has dissipated. Soon after Liz departs, the Brigadier walks in unexpectedly, and the Doctor learns he didn’t send for them. Lethbridge-Stewart immediately gets after Liz, who is now on her way to Hertfordshire in Bessie. Another car staked out on a side road waits for her to pass, then takes chase from behind, and Liz fights to stay ahead of it. However, the horsepowerof the modern vehicle quickly outpaces the vintage car and overtakes Bessie on a straight patch of road. Liz is forced to stop and bail out in a sprint, where Reegan’s henchmen attempt to capture her. The chase leads to a pier, where Liz fights off one man but slips over a railing as another man grabs her by the legs, and she dangles helplessly above a death drop.


Despite Liz hanging off the edge of the bridge, she does not evade her captors and is brought to the lab where the astronauts are being kept to help Lennox.

Carrington has issued a police alert for the return of Liz. He has also found some documents in a foreign language in the lab that, he thinks, proves that the astronauts have been stolen by a foreign country to be used as a weapon. The Doctor thinks that this is a plant and that the astronauts are still in space. He wants to decipher the impulses sent originally. Carrington says it is futile, but that does not put The Doctor off.

Cornish and Taltalian are calculating how to get the capsule into space and are having to cut corners because of the blocks that Sir James is putting into place. The Doctor enters, and he and Taltalian make up. Cornish asks after Liz, and the Doctor says there is no news. The phone rings. It is for The Doctor. He is told that unless he stops interfering Liz will be killed. He hangs up and continues to decode the message.

Liz is helping Lennox, who sends a guard out to tell Reegan there is only one canister left. Whilst the guard’s back is turned, Liz tries to run, but the door is locked. When she returns, she is scornful of Lennox’s involvement in the project. He says he has nowhere else to go. As Lennox prepares to enter the quarantine, he hands Liz a key and tells her to lock him in the quarantine and run. She does so.

The Doctor has cracked the code. It is instructions to build an electronic device. He questions Taltalian and says he is still an informer.

Liz sneaks out and runs through the forest.

Taltalian is shocked that The Doctor has accused him. The Doctor says that he can either confess to him, or he can be interrogated by the Brigadier. He leaves to build the machine. Left alone, Taltalian picks up a device and leaves.

Liz attempts to hitchhike. A car pulls over, but it is Taltalian behind the wheel. He pulls a gun on Liz and tells her to get in. She is returned to the lab, where she tells Reegan that the door was left open. Taltalian hands the device over to Reegan, saying that the creatures will respond to the commands that are given to them, and if they don’t, they can threaten to cut off their radiation. Taltalian says that Reegan is to conduct a series of raids on targets. Taltalian berates Reegan for calling The Doctor, saying that it only got his ire up and that he needs to be put out of way before he constructs anotherone of the machines. Reegan says he will deal with it.

The Doctor tells the Brigadier about his suspicions regarding Taltalian, but he has no pro of. The Brigadier is unsure, but The Doctor says he doesn’t believe any of it. The Doctor requests a list of equipment and leaves, not before asking of any news regarding Liz.

Lennox surreptitiously thanks Liz for not grassing on him. Liz is determined to escape again.

In another room, Taltalian is anxious to return. Reegan gives Taltalian a bomb with which to kill The Doctor. He sets it for fifteen minutes but, while Taltalian’s back is turned, changes it so it will explode straight away.

Cornish is frustrated. All available astronauts have been transferred by Sir James. The Doctor volunteers to pilot the capsule. Cornish questions whether he has the ability to do so. The Doctor says he has spent more time in space than all of his astronauts put together and can face any tests required. Taltalian returns, and Cornish asks if he has the computations for the capsule left. Taltalian stalls him, and Cornish leaves. The Doctor asks if he has thought of the deal he offered him. Taltalian says he will tell The Doctor everything if he allows him to get away. He says he needs to go to his car for the information. He sets the bomb, which explodes instantly.

The device that Taltalian gave Reegan can control the astronauts.

The Brigadier and the Doctor pick through the debris in the lab. Taltalian is dead, betrayed by Reegan. The Doctor finds anotherone of the controllers in Taltalian’s possession.

Sir James tells Carrington that he has done everything to block Cornish’s flight, but he can’t delay anymore. Sir James suggest they tell the truth, but Carrington says they cannot do that, despite the launch of the capsule leading to a disaster for the entire world.

Reegan shares his disappointment at the survival of the Doctor with a superioron the phone. Once he is off, he calls for a van and says that the astronauts are going on an excursion. Reegan asks Liz if the controllers can go the other way and if the astronauts can communicate with them. Liz says that it is possible, but something would have to be created.

Later, an astronaut strides towards the main gates of the Space Centre. The sentry on duty warns the intruder “Halt!” The spacesuited figure fails to do so, continuing its approach, and likewise fails to comply with the sentry’s second warning, “Halt or I’ll fire!” The guard fires at the astronaut, but the bullets have no effect. The astronaut radiates the barrier simply by touching it and the guard is blasted to the ground. The astronaut lifts the barrier and continues on his way, entering a computer workstation where he kills two scientists with its radioactive touch. The astronaut starts to search the workstation and opens a cupboard, reaching for something inside. A guard enters with a machine gun, which is also ineffective against the astronaut. The guard is killed in the same way as the scientists.

The Doctor has discovered that the device translates alien impulses into human speech and wants to build the other part of the machine. The Brigadier says he is trying to deliver as much equipment as possible, but they are coming from Japan. The phone rings. It is Sir James for The Doctor. He asks if tThe Doctor can be dissuaded from piloting the capsule. The Doctor says only if he is told the truth. The Doctor agrees, and he and the Brigadier make their way to see Sir James.

The astronaut enters Sir James’s office and kills him. The astronaut uses his radioactive touch to open the safe and destroy the contents. The Doctor enters and sees Sir James dead. As he checks him over, the unseen astronaut approaches The Doctor from behind, reaching out with his right hand.


As the astronaut bears down on The Doctor, the Brigadier enters and shoots at it. The astronaut turns and rounds on the Brigadier. The astronaut escapes, killing a UNIT soldier as it leaves. It radiates the lock behind it as it goes, sealing the door and trapping The Doctor and the Brigadier inside.

Liz speculates that the astronauts are not human and questions Lennox as to whether Reegan is in charge. Lennox tells her that Reegan answers to someone higher up. Liz tells Lennox she has a plan for him to escape.

The Brigadier shows The Doctor the bullets he fired at the astronaut. They are dented. The Doctor says they have been deflected off a kind of force field. A UNIT soldier says that there are strong traces of radiation leading outside the building and then it disappears. The Brigadier says this is pro of that the astronaut was collected by a vehicle. The Brigadier wonders what the purpose of all this is and speculates if it is conquest. The Doctor states that this is what they are supposed to think.

The astronaut is returned to the lab.

Cornish is explaining the capsule to The Doctor. He explains that, due to the blocks already established before Sir James’s death, they have had to mix standard fuel with a type of fuel named M3 which has never been done before. The Doctor’s medical report is presented to Cornish. He seems confused by it, but The Doctor swiftly moves on.

The astronaut collapses as soon as it is back in the quarantine. Lennox re-radiates it. Liz asks Reegan what it has been doing. Reegan explains it has been killing her UNIT friends. When he leaves, Liz accuses Lennox of facilitating murder. Liz says that Lennox should go to the Brigadier and that she can help him talk his way out.

Carrington enters the Space Centre and tries to block the launch of the capsule. Cornish points out he does not have the rank to do that. Carrington says he is convinced that this is an alien invasion with the collaboration of a foreign power. The Doctor points out that this does not explain why he opposes it. Carrington says that he believes the capsule should carry a nuclear warhead instead. Carrington says he is going to take his objections to the highest level. Cornish says that he had better hurry as they will be launching in two hours.

The astronaut is recovering. Liz and Lennox are still squabbling. Liz tells Lennox to tell the guard he needs more isotopes and that he needs to see Reegan. Lennox tries this, but is blocked. Liz fabricates a story about the astronauts dying and convinces the guard. He still does not let Lennox leave, but Liz convinces him that the death of the astronauts will be on his hands. Lennox also adds that he is not a prisoner. The guard is convinced and frees Lennox.

The capsule is ready, and the Doctor is summoned to the preparation room. The Brigadier asks The Doctor why the launch time has been brought forward. The Doctor explains it has been done to thwart Carrington. There is a call for the Brigadier. It is Sergeant Benton, who says that a man named Lennox is desperate to see him and is frightened out of his wits. The Brigadier tells Benton to put him in a cell until he has a chance to speak with him.

Lennox is led to the cell and is unsure of its safety. He implores the guard to lock the door.

The Doctor is ready for the launch. The Brigadier says goodbye, and the Doctor proceeds to the capsule.

Reegan is cross at the guard for letting Lennox go. The guard blames Liz. Reegan grabs her and puts his gun to her head, demanding to know where he went. Liz says he went to the Brigadier. Reegan rushes to the phone and calls someone. He says that they are to take care of Lennox while he will take care of the Doctor.

Cornish is performing an instrument check on the capsule. The Doctor is very impatient and only gets more so when told he is still thirty-three minutes away from launch. He is told that the fuel is taking a long time to load and that they have to get the balance between standard and M3 fuel just right, otherwise the ship will blow up in orbit.

A man tries to infiltrate the Space Centre dressed as a mechanic. He knocks a guard unconscious and begins to climb the scaffolding around the launch site. He kicks a worker that tries to stop him off the side. He begins to turn valves around the launch pad.

A fuel injection malfunction registers in the Space Centre. Cornish is concerned, but it soon self rectifies.

The man is still making his way around the launch pad, knocking out any workers that he comes across. He turns a large valve on a cylinder marked “M3 Fuel”. He climbs higher and higher, turning valves as he goes, and then makes his escape.

Food is brought to Lennox. As the guard leaves, he implores for the door to be locked. He takes the lid off his food and finds an isotope. Horrified, he presses the panic button, but there is no response.

The Brigadier finds the groggy soldier whom the saboteur knocked out. He rushes out and investigates, seeing the damage he has left.

At the Space Centre, they are all set for take off. The countdown begins when the Brigadier rushes in and orders the take- off to be cancelled. Cornish ignore him and the rocket takes off.

The Doctor is sustaining huge amounts of G force and the rocket’s speed is 20% higher than it should be. The fuel burn will not reduce, and the Doctor is at risk of blowing himself out of Earth’s orbit and into the Sun. Cornish implores The Doctor to try to control the fuel burn manually, but the heat has corrupted the controls. The rocket’s speed is now 37% higher than it should be. The Doctor tells Cornish to jettison stage one of the rocket, but Cornish is reluctant to as it will mean The Doctor would struggle to get into orbit. The Doctor points out that it is the only option they have. Cornish orders the jettison. This stabilises the rocket and returns the speed to normal. The Doctor is informed of the saboteur.

Later Cornish is directing a very casual Doctor towards Mars Probe Seven. The Doctor links the capsule to the probe and unbuckles himself, ready to move into the probe. Cornish urges caution, but The Doctor is calm. As he opens the hatch, Cornish warns of a UFO in collision with The Doctor and orders evasive action. The Doctor looks out the window and sees a large red disc approaching him.


The red disc is a spaceship. The Doctor tries to evade it, but he doesn’t have enough speed as he is still linked to Mars Probe Seven. The Space Centre loses communication with him. It has collided with the ship. The capsule must be smashed to fragments.

The Doctor awakes inside his capsule. A voice tells him he is not in danger and that he can leave his capsule. The Doctor reaches for his space helmet, but is told he won’t need his space suit as an environment has been prepared for him. He asks where the astronauts are, and is told they are unharmed.

The Doctor walks out into a large red tunnel and is told by the voice to walk into the light. There, The Doctor finds himself in what appears to be the Space Centre’s quarantine area, where the astronauts watching a game on a screen and are in good spirits. The men are under the assumption that they are in extended quarantine on Earth. The Doctor tells them the truth, but they don’t believe him. Suddenly, a strange noise hypnotises the astronauts, and they no longer respond to The Doctor. An alien figure appears on a giant video screen, explaining that the astronauts have had their minds conditioned to stop their minds deteriorating. The figure wants to know why their ambassadors have not been returned and warns that unless this happens, Earth will be destroyed.

The Space Centre have discovered that the ship is half a mile in diameter. Carrington wants to attack and destroy the ship. The Brigadier says they cannot do that with The Doctoron board, but Carrington says he is most likely dead anyway. Carrington leaves for Geneva to push for an all-out attack. The Brigadier shocks Cornish when he seems to be somewhat on the side of Carrington, but the Brigadier also thinks that Carrington has more information than he is letting on. Theironly hope is The Doctor.

The Doctor says the authorities on Earth have no knowledge of the ambassadors, but the alien figure finds that hard to believe. The Doctor asks to go back to Earth, assuring the ambassadors will be returned. The alien agrees to this, but echoes his previous threat to destroy Earth. The Doctor asks if the astronauts can come with him, but the alien says they are to remain as hostages until the ambassadors are returned. The astronauts return to consciousness, and the Doctor leaves them in blissful ignorance that they are in quarantine.

The Space Centre learns that NASA are launching an observation satellite to monitor the spaceship due to the fact that it is emitting radio signals. The Brigadier tells Cornish of the murderof Lennox. Cornish is starting to question UNIT’s efficiency. The Brigadier lists what has been discovered already. The bodies in the gravel pit belonged to petty criminals, the bomb that killed Taltalian was an experimental bomb being refined by the army and not for general use yet, there was insecticide on Lennox’s shoe that they are tracking to local countryside and the isotope used to kill him was sold to a company that no longer exists. Cornish takes back his questioning of UNIT’s ability. The Space Centre is alerted that the radio signals have stopped. The Doctor returns on the video screen. He says that the astronauts are safe and well, but he can’t say anymore as it is not safe. He explains he is going to land and that UNIT’s men should be on standby. The Doctor breaks communication and starts re-entry.

Liz is radiating the ambassadors when one of them stops her from leaving. It lifts up its helmet to reveal an alien face. Terrified, she escapes. She shows Reegan, who seems nonplussed. He tells Liz of the death of Lennox and offers her his job. The phone rings. Reegan is told that The Doctor is returning from space and that he is to be killed. Reegan sets off.

The Doctor is four and a half minutes from touchdown. The Brigadier wants to go and meet him, but Cornish tells him it will take him an hour to get through decontamination.

A lorry approaches the Space Centre. Reegan is driving and produces some papers. He is waved through.

The lorry draws up at the decontamination unit ventilation system. Reegan sets about fiddling with pipes and gauges.

The Doctor enters the decontamination unit. Reegan puts a gas canisteronto one of the pipes.

The Doctor is told that they are awaiting the test results and that he has to stay in the decontamination unit longer. He lies down. A gas starts to enter through a vent, and he starts coughing. He tries to rise up but falls to the ground.

Reegan stops the gas and enters the decontamination unit wearing a gas mask. He picks The Doctor up and drags him out.

Cornish is told that all the tests are negative and tells The Doctor that he can leave decontamination. There is no response. The Brigadier rushes off to investigate.

The Brigadier enters and discovers the gas and the Doctor gone. He tells Cornish and orders the gates sealed, but it is too late; the lorry has already left.

The Brigadier reports the abduction of the Doctor. Carrington thinks it is a blind and that The Doctor is working with the aliens. He questions the Brigadier about how much he knows about The Doctor. Carrington says he is going to investigate The Doctor and then blast the spaceship out the sky.

Reegan tells his superior that The Doctor is dead, but it is not true. The Doctor comes to and is reunited with Liz. He investigates the ambassadors and tells Reegan what he saw. When Reegan asks how he communicated with them, The Doctor says they have a translation device. Reegan shows The Doctor the one that Taltalian gave him, and the Doctor states it is far more complex than that. Reegan asks if The Doctor can build one; he says that he can, but he won’t. Reegan says he will kill him unless he does. The Doctor sits down to make a list of the equipment he’d need. Reegan leaves them. The Doctor tries to escape, but Reegan is loitering by the door. Liz tells The Doctor about her failed escape. The Doctor sits at the desk and starts making the list, telling Liz that if they can’t get to the Brigadier, maybe his list might bring the Brigadier to them. Carrington enters, armed. Carrington reveals himself to be Reegan’s superior, and seeing as Reegan didn’t follow his orders and kill him, he will have to do it himself.


Reegan enters and begins to argue with Carrington, saying he kept The Doctor alive as he is the only man who can make the translation machine to help them communicate with the aliens. Carrington realises that Reegan is alive. The Doctor questions Carrington as to what his plan is. He says he wants to alert the world to the menace of the aliens. The Doctor says he knows these aliens seek no ill will. Carrington is convinced that they are hostile and tells a story of how he first encountered them on Mars, where they killed Jim Daniels, his fellow astronaut. The Doctor states they probably didn’t know their touch was fatal to humans and wouldn’t have intended to harm. Carrington will not be dissuaded and says that they have walked into his trap whereby he will convince the world they are evil. He says that he is the only one who knows of this plan and that no-one else has helped him. The Doctor agrees to continue making the machine. Carrington tells Reegan that he wants to take an alien with him.

NASA’s satellite is within three miles of the UFO and drawing in.

The Space Centre receive news that there is no signal from the satellite and that it has disintegrated. The Brigadier receives a phone call from Carrington, who tells him he has captured one of the astronauts and is bringing it to the Space Centre.

Reegan implores The Doctor to be quicker in the construction of the machine. He takes the aliens away with him, despite The Doctor trying to convince him otherwise. Reegan says he wants the machine finished on his return. The Doctor continues construction of the machine, much to Liz’s surprise.

The van draws up to the isotope store. The ambassadors leave the van and break through the fence, radiating a guard. The alarm is raised. The van enters.

Carrington is preparing a live video cast wherein the alien is going to be revealed. The presenter, Wakefield, questions if this is not going to raise a panic.

Reegan sets about stealing isotopes. The police rush to the scene as Reegan is loading them onto the van. The ambassadors radiate the policemen, but do not kill them.

The Brigadier tells Carrington of the isotope robbery. Carrington says that this proves that the aliens are dangerous, and the fact that they are accompanied by men proves that there are traitors in their midst. Again, he accuses The Doctor of being in league with the aliens. He tells the Brigadier that he will tell the world to unite against the aliens on his broadcast.

The ambassadors are back in quarantine. The Doctor has finished his machine and is about to test it. Conspiratorially, Liz asks if the signal is strong enough. The Doctor begins to tap Morse code whilst pretending the machine isn’t working.

The Doctor’s Morse code is being picked up by all number of different radio receivers, including UNIT. They set about triangulating the signal.

Wakefield and Carrington are going through a dress rehearsal of the broadcast. Cornish talks to Wakefield and tries to persuade him to not broadcast.

Reegan questions The Doctor about what is taking so long. The Doctor says he is ready to test. He tries to talk to the ambassadors. There is no reply. He tries again. Again, no reply. The third time the ambassadors turn and ask why they are being kept prisoner and why they are being used to kill. Reegan snatches the machine’s microphone away from The Doctor and threatens the ambassadors. If they do not do what he says, they will be left to die. The ambassadors say they came in peace, but Reegan tells them if they want to live, they’ll do as he says. Pleased with the machine’s success, Reegan congratulates The Doctor, saying he can use the machine to “make a few plans”. The Doctor reaches for the microphone, but Reegan warns him “Leave it.”

The UFO communicates with the Space Centre, with the alien figure appearing on the large video screen in the control room. The alien says they have little time, and if their ambassadors are not returned they will turn all their powers against Earth. Carrington says they must now attack and that he needs to broadcast immediately. Wakefield says he can’t for another hour, and Carrington tells him to hurry. Cornish tries to dissuade again, but it falls on deaf ears. The Brigadier tells Carrington of the SOS signal being picked up, and he suspects it is The Doctor. Panicked, Carrington has the Brigadier arrested, saying that he too is in league with the aliens. The Brigadier is told that all his UNIT men have been arrested and replaced with men loyal to him. Cornish tries to ring the ministry, but Carrington says he has cut communication and is now in charge of the Space Centre.

The Brigadier disarms the guards and steals a staff car, managing to escape from the Space Centre before the alert is raised. He arrives at the radio communication centre where they have triangulated the signal to a disused firing range not far from the Space Centre. The Brigadier starts to see Carrington’s hand in all of this. He is told there is only one mode of transport to get to the firing range — Bessie. The soldiers pile in and reach the firing range. They arrive as some men leave, and a fire fight ensues. The men run out of bullets and, seemingly, surrender, but as they draw near a fist fight breaks out. One man is shot whilst the Brigadier throws anotheroff the edge of the cliff.

Inside, Reegan is trying to convince The Doctor to work alongside him. They hear the gun shots and the Brigadier enters, shooting the guard and injuring Reegan. He explains Carrington’s plan to The Doctor. Reegan suggests they could use the ambassadors as a way of getting back into the Space Centre. The Doctor explains the plan to the ambassadors.

Bessie and the van draw up to the entrance of the Space Centre. The Brigadier asks the men to open the gates, but they refuse. The ambassadors are let out of the van. The Doctor tells them to open the gates and to try not to harm anyone. The soldiers shoot at the ambassadors, to no avail. The Doctor tells the soldiers using a megaphone that the aliens are invulnerable to bullets, and warns “They will not harm you, but you will die if you touch them.” The soldiers fall back, the ambassadors open the gates and Bessie and the van drive in.

Carrington and Wakefield are still going through the dress rehearsal. Cornish implores with Carrington again, and Carrington has Cornish taken away by security. They are five seconds from broadcast. As Wakefield introduces Carrington, a banging is heard and then screams from a female technician; Wakefield hastily signals for the transmission to be cut. The ambassadors enter, followed by The Doctor, the Brigadier and the UNIT soldiers. The Brigadier arrests Carrington. As he is led away, he tells The Doctor that he had to do what he did. The Doctor releases the captive ambassador and says a message needs to be sent to the UFO. Cornish asks after his astronauts, and the Doctor says that they are safe. All that needs to be done now is to send the ambassadors up in Mars Probe Seven and the aliens will send down the human astronauts. Even the issue of fuel isn’t a problem. The ambassadors are immune to g-force so they can use the M3 variant. The Doctor bids Cornish farewell. Liz is to stay in and help with the exchange. As he leaves, The Doctor goes to shake the ambassadors’ hands before thinking betterof it and wishing them a nice trip.


  • At the start of the adventure, The Doctor has not yet forgiven the Brigadier for his destruction of the Silurian base.
  • The Doctor is fixing the TARDIS‘ Time Vector Generator, which sends Liz fifteen seconds into the future.
  • The Doctor and Liz receive data from real life radio telescopes: Haystack Observatory and Catalina in the US, Algonquin in Canada, Arecibo in Puerto Rico,
  • Mullard Radio Astronomy Observatory (“Cambridge”) in the UK, Culgoora in Australia, Dwingeloo in Holland, Nancay in France, and Onsala in Sweden.
  • The Doctor can make solid objects vanish and, a few minutes later, reappear”, a method he refers to as “transmigration of object”. This is the first story to feature Benton with the rank of Sergeant.
  • Liz can speak French.
  • The aliens are not native Martians.
  • The aliens‘ radioactivity is suggested as being conductible like electricity.
  • General Carrington suggests sarcastically that The Doctor has nine lives.
  • Carrington uses the Military Police to arrest the Brigadier and his men.

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