2197. The fighter-carrier Valiant has just crossed Pluto's orbital path. Its captain is expecting trouble from alien raiders. She is not expecting the Doctor and Evelyn. She does not believe members of her crew when they say they can hear an ancient bell ringing. A bell that strikes terror into their hearts. 1952. The Turret Class locomotive Ivy Lee is hurtling through the night. On board, there should only be two passengers: both of them carrying documents from the War Office. The Doctor and Evelyn have arrived and "Time's End" is approaching.