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.

But now, there are also two unexpected visitors on the train. One is the guard with ill-fitting trousers, the other is an excessively dotty old lady.

The Doctor and Evelyn have arrived and 'Time's End' is approaching.