Doctor Who: Mawdryn Undead

A warp ellipse draws the TARDIS off course. The Fifth Doctor's companions are separated from him not in space, but in time, and he has to deal with a treacherous schoolboy named Turlough. But why does the Doctor's old friend, the Brigadier, not remember him at all?

Doctor Who: The Deadly Assassin

Summoned back to Gallifrey, the Doctor is framed for the assassination of the Time Lord President. To prove his innocence, he must stand for election himself, uncover the traitor in the Time Lord High Council, fight a hooded killer in a nightmare cyberspace world of his enemy's devising and battle against an old foe now out to destroy the Time Lords: The Master.