(BARBARA suddenly realises what has been going on.) (He begins giggling. (IAN and BARBARA walk away. (IAN and the DOCTOR mutter to each other as SUSAN discusses the fast return switch with BARBARA.) (IAN is recovering slowly again on the floor.) (The DOCTOR crosses to the table and lifts a coat from it. All four of us are to blame! And it replaced time, by the light on the fault locator. DOCTOR: ... strange. DOCTOR: If, of course, they'd like to confess to me what they have done to my ship, I may even change my mind. DOCTOR: Yes, it must have been. IAN places his hand on the DOCTOR'S shoulder and BARBARA and SUSAN walk up to the console. IAN: A machine that can think for itself? It means, that the ship is on the point of disintegration. Of course! SUSAN enters.) SUSAN: (Shocked.) She turns back to IAN.) Something outside? TARDIS. TARDIS. TARDIS. The DOCTOR taps him on the shoulder and returns to the control panel.)
Plan: A: the TARDIS floor; Q: Where were the Doctor, Susan, Ian and Barbara thrown to? A: Susan; Q: Who is the Doctor's companion who is acting strangely? A: suspicions; Q: What is raised that an alien force may have entered the ship? A: The Doctor; Q: Who accuses Ian and Barbara of sabotage? A: the travellers; Q: Who realizes that the TARDIS is trying to warn them of something? A: an attempt; Q: What does the TARDIS itself reveal to be happening to warn them of something? A: time; Q: The Doctor realizes that the fast return switch he used when leaving Skaro has stuck, and the ship has been plunging back to the beginning of what? A: its own destruction; Q: What does the TARDIS go back to the beginning of time to see? A: a faulty spring; Q: What is the problem with the fast return switch? A: his behaviour; Q: What does the Doctor apologize for? Summary: As they slowly recover from the shock of being thrown to the TARDIS floor,the Doctor, Susan, Ian and Barbara all seem to be acting strangely. Unexplained events occur and suspicions are raised that an alien force may have entered the ship. The Doctor even accuses Ian and Barbara of sabotage. It gradually dawns on the travellers that what they have been experiencing is an attempt by the TARDIS itself to warn them of something. The Doctor finally realises the fast return switch he used when leaving Skaro has stuck, and the ship has been plunging back to the beginning of time and its own destruction. Once the problem - a faulty spring - is corrected, the TARDIS returns to normal and the Doctor has to make some apologies for his behaviour.