The Edge of Destruction, episode 1
8 February 1964
Having defeated the Daleks and escaped Skaro, the TARDIS is subject to a violent jolt. When the crew awaken, they are changed: Susan is malevolent, the Doctor hostile, and Ian and Barbara the subject of suspicion. The TARDIS doors open and close in flight. Has something got into the ship with them? As the Doctor and Ian check the fault locator, Susan attacks Barbara.