Keith Goodman

The TARDIS arrives in 2070 on the Moon, where a weather control station under the command of a man named Hobson is in the grip of a plague epidemic — in reality the result of an alien poison planted by the Cybermen. Jamie is knocked unconscious and lapses into a delirium, leaving the Second Doctor, Ben, and Polly to fight off a massive Cyberman attack.

The Police investigate the theft of emerald jewellery which had led to murder.