Doctor Who: Full Circle, Episode 4 (1980)

Synopsis
In the conclusion of the four-part story "Full Circle," the Doctor (Tom Baker) has discovered that the marooned passengers of a crippled starliner have had it within their power to escape Alzarius for centuries. The trouble is, the passengers are unaware of this -- or rather, they don't seem to want to be aware. Will the Doctor be able to realign their thinking, and thereby wrest himself free of E-Space so that he can answer an urgent summons from his fellow Time Lords? Matthew Waterhouse joins the regular cast as the Doctor's new companion Adric. Written by Andrew Smith, "Full Circle, Episode 4" was originally telecast on November 15, 1980. ~ Hal Erickson, All Movie Guide