When Tarrant of British Intelligence finds himself a prisoner facing weeks of mind-bending interrogation, he clings to one slim hope - that Modesty Blaise and her formidable henchman, Willie Garvin, will suspect his well-faked death in a road accident and will find him before he breaks.

His captors are a bizarre company led by Colonel Jim, a criminal tycoon who aims to do for blackmail what Ford did for motors. There is Angel, the girl with the wire garotte; Mrs. McTurk, the genteel assassin; and the unique Mr. Sexton, who rightly claims to be the greatest combat-man in the world.

It is in Macao that Modesty and Willie discover the vital lead to Tarrant's whereabouts. When they return to move against the remote Chateau Lancieux, in the Pyrenees, where he is held, they are not alone. With them is Quinn, the embittered young flyer who knows a secret way into the chateau, and Willie's titled girl-friend, Lady Janet, who has her own part to play. But their plans go badly awry, for Modesty and Willie meet their match at last in Mr. Sexton, and Tarrant's rescuers become captives with him.

The story moves to its climax with a nerve-twisting escape from the chateau and a final confrontation between Modesty and Mr. Sexton, deep underground in a great stalactite chamber of the Lancieux Caves.