A former British Secret Service agent is persuaded to negotiate a spy exchange with Russia, only to find himself drawn into political intrigues.

Teenagers gathered in an old mansion are being murdered one by one. The survivors must discover who among them is the killer before he finishes off everybody.

A Scotland Yard detective is investigating a string of robberies and a murder, and the information he uncovers leads him to the estate of a wealthy but strange English family, who share their mansion with a group of nuns. The detective comes to suspect that neither the family nor the nuns is quite what they seem to be.