Tommy and Tuppence Beresford are restless for adventure, so when they are asked to take over Blunt's International Detective Agency, they leap at the chance.

Their first case is a success—the triumphant recovery of a pink pearl. Other cases soon follow—a stabbing on Sunningdale golf course; cryptic messages in the personal columns of newspapers; and even a box of poisoned chocolates. But can they live up to their slogan of "Any case solved in 24 hours"?