Roger Delgado (The Master), Edwin Richfield (Captain Hart), Clive Morton (Trenchard), Royston Tickner (Robbins), Neil Seiler (Radio Operator), Declan Mulholland (Clark), Hugh Futcher (Hickman), June Murphy (3rd Officer Jane Blythe), Alec Wallis (Ldg. Telegraphist Bowman), Brian Justice (Castle Guard Wilson), Terry Walsh (Castle Guard Barclay), Pat Gorman (Sea Devil), Eric Mason (C.P.O. Smedley), Donald Sumpter (Commander Ridgeway), David Griffin (Lt. Commander Mitchell), Christopher Wray (Ldg. Seaman Lovell), Stanley McGeagh (Castle Guard Drew), Colin Bell (C.P.O. Summers), Brian Vaughan (Lt. Commander Watts), Rex Rowland (A/B Girton), Martin Boddey (Walker), Norman Atkyns (Rear Admiral), Peter Forbes-Robertson (Chief Sea Devil), John Caesar (C.P.O. Myers).
|Written by||Malcolm Hulke|
|Directed by||Michael E. Briant|
|Produced by||Barry Letts|
The Doctor and Jo Grant visit their old enemy The Master, who is the sole inmate of a top-security prison on a remote island off the south coast of England. Local shipping has been plagued by a series of tragic accidents and several ships have been lost. Joining forces with Captain Hart of the HMS Seaspite naval base, The Doctor learns that there have been garbled reports of sea monsters. Colonel Trenchard, Governor of the Master’s prison, believes that the ships are being attacked by enemy spies. The Master himself seems to be a reformed man and claims to have turned away from his life of crime.
Nothing could be further from the truth. The Master has in fact made contact with the Sea Devils, aquatic cousins of the prehistoric Silurian race encountered by The Doctor some time ago.
Having slept beneath the sea for millions of years, the Sea Devils have awoken and intend to reclaim what they consider to be their planet.
Aided and abetted by the evil Master, who will stop at nothing to take revenge on those who imprisoned him, the Sea Devils plan to eliminate the human race, a species they regard as nothing more than upstart apes