The TARDIS has materialised inside an abandoned rocket drifting in space. The Doctor and Jamie are taken to a nearby space station, and its controller orders the rocket destroyed by the Wheel's laser gun - with the TARDIS still on board! There is another alien presence on the rocket, too: strange eggs which begin to hatch out ... to what?
The DOctor has a double: Salamander, inventor of the 'sun-store', who has saved the world from starvation. Giles Kent, once Salamander's ally, suspects his real aim is to seize power. The Doctor falls in with Kent, while Jamie and Victoria are given jobs in Salamander's retinue. After a volcanic eruption in Hungary, political leader Denes accuses Salamander of creating the disaster himself, but Salamander responds by having him deposed and arrested ...