The Doctor and Jamie are taken prisoner by their mysterious observers and have a reunion with an old friend while Zoe and Isobel carry out their own investigation of IE.
Quest roles:
Nicholas Courtney(Brig. Lethbridge-Stewart), Kevin Stoney(Tyrum), John Levene(RSM Benton), Geoffrey Cheshire(Jack Tracy), Sally Faulkner(Isobel Watkins), Peter Halliday(Pletrac), Ian Fairbairn(Doctor Chester), James Thornhill(Sergeant Walters), Robert Sidaway(Captain Turner)