An Iron Curtain agent is using a young girl to extort secrets from, and ultimately destroy the career of, a future British Prime Minister, unaware that the girl is the long-lost daughter of a well-known local prostitute.

CI5 become aware that an assassination plot on a group of visiting Greek Royals is being planned using a rifle that has a range of over two miles. But they must find out who is the gunman and what is his target - before it is too late.

CI5 are left to dig deep when an Israeli Minister is kidnapped, and the only clues to his whereabouts are a shadowy photograph and a coded tape message.