Doctor Who episode 554: Castrovalva – Part One (4/1/1982)
‘If escape were that easy Adric we could all be free of this nasty world.’ While previous regenerations have picked up from the end of the previous story, this is a straight continuation of Logopolis 4, with the amazing vanishing security guards reappearing to menace the new Doctor and friends, the Master having come up with yet another plan on the fly, and references to block transfer and the Logopolitans. This makes sense as a follow up to The Five Faces of Doctor Who, which concluded with Logopolis in December 1981. The plus is that it provides immediate jeopardy directly connected to the Doctor’s regeneration.