Doctor Who: The Web of Fear - Episode 3

In order to escape an attack in space, the TARDIS makes an unscheduled landing and ends up deep inside the London Underground. Here the travellers soon find themselves engulfed in a thrilling battle with the Great Intelligence and the Yeti, a deadly enemy set to invade the Earth. But as events take a turn for the worse, it becomes clear that the golden prize is not just the Earth, but the Doctor's mind too.