Joy Harrison

Cardiac surgeon Alex Marsden has an affair with Marcella Duggan, but then finds himself having to operate on her husband Larry, who is also his friend.

An energy drain traps the Third Doctor and Sarah Jane Smith on the planet Exxilon with its hostile natives, causing the travellers to make an uneasy alliance with a Marine Space Corps expedition and a squadron of Daleks. The key to escape for all of them lies at the heart of a powerful and mysterious lost city, but only after a series of deadly traps.