In England a hotel worker has been turned to stone, an ancient lake has vanished, and the inmate of a mental hospital is being terrorised by unseen creatures. In Israel, in the shadow of Masada, an archaeological dig unearths something that should have stayed buried. The Doctor is sure he is dealing with a local and relatively straightforward temporal anomaly. Troy Game, a refugee from the planet Caresh, is not so certain. She believes the impending destruction of her home world is somehow linked to the events on Earth, and she is pinning her hopes on the Doctor to avert the catastrophe. But can the Doctor interfere with a planet's destiny? And should he risk his new-found freedom to do it?