The Doctor and Jeremy have landed on Sedna. The Doctor has been here before, and recognises, to his dismay, the style of the architecture as being Siccati. He realises that the Siccati attacked their own colony world on Neptune when he visited with Sarah. Jeremy, however, gets lost and finds himself in a cavern, in which there is a huge egg-shaped device suspended over a shaft. Jeremy realises it is a bomb and heads back to find the Doctor and tell him of his discovery.