The Doctor, Jamie, Polly and Ben arrive on New Houston, an Earth colony in the Fourth Sector, which the Doctor previously saved from an alien invasion.
The TARDIS lands on an island off Singapore during the Japanese invasion of 1942. The travelers are found by some British soldiers - among them a certain Private James Jackson.
On a research station near a black hole, time keeps standing still. Investigating the phenomenon, the Doctor, Jamie and Victoria discover a power far greater than any of the monsters that have challenged them on their travels.
The Doctor, Jamie and Zoe are leaving Earth after having successfully defeated a Cyberman invasion - The Cyber-fleet is still exploding - But something is escaping through the mass of vaporizing debris.