15 December 1973
Nicholas Courtney (Brigadier Lethbridge-Stewart), Kevin Lindsay (Linx), Donald Pelmear (Professor Rubeish), David Daker (Irongron), John J. Carney (Bloodaxe), June Brown (Eleanor), Alan Rowe (Edward of Wessex), Jeremy Bulloch (Hal), Sheila Fay (Meg), Gordon Pitt (Eric), Steve Brunswick (Sentry) 
|Written by||Robert Holmes|
|Directed by||Alan Bromly|
|Produced by||Barry Letts|
A spacecraft crashes near the castle of a robber baron in the Middle Ages, and the Sontaran Warrior within needs help with its repair. Unable to obtain the technical expertise he requires, he ventures forward in time to the 20th century and begins kidnapping scientists.
This attracts the attention of UNIT and the Doctor, who follows the trail back through time, unknowingly taking a young stowaway with him…
Working titles for this story included The Time Fugitive and The Time Survivor.