Maurice Castle is a high-level operative of the British Secret Service during the Cold War era. Deeply in love with his African wife, Castle decides with misgivings to act as a double agent to help his in-laws in South Africa. Eventually Castle begins passing information to the Soviets. In order to evade detection, he allows his assistant to be wrongly identified as the source of the leaks. But when suspicions remain, Castle is forced to make an even more excruciating sacrifice to save himself.
