London 1910: An unsuspecting thief gets more than he bargained for when he breaks into a house in Kensington. He finds himself confronted by horrific, grey-skinned creatures waiting to devour his mind.
London 3189: An unimaginably ancient city. The remains of an android are dredged from the Thames. It's one of the latest models, only just developed. But it's been in the water for over a thousand years.
The Doctor and his friends must solve a mystery that has spanned a millennia. Traveling backwards and forwards in time, they must unravel the threads of an ancient plot. If they fail, the deadly alien Squall will devour the world!