Spy Philip West is sent by Sir Iain to investigate the disappearance of several British agents in Lisbon. But he is captured by the opposition and interrogated.

A Russian bomber jettisons two nuclear warheads just outside Bulgaria. Sir Iain is ordered to photograph the missiles before they are retrieved. But they are held in a maximum security police headquarters at the fishing village of Borku, and there is less than twenty four hours in which to act.

Goric, a foreign agent, comes to Britain to attend a chess tournament where he will receive some top secret microfilm.

Unfortunately he becomes indisposed so Philip West goes in disguise - having hopefully brushed up on his knowledge of chess.