The peace of a quiet day is disturbed at Quinns, the antique shop in London's Mayfair owned by John Mannering – known also as 'The Baron' and a former master cracksman and jewel thief. The phone rings and is answered by Josh Larraby, himself a former thief. 'They're trying to kill me' pleads the man on the line. Then laughter is heard, at first soft, but rising to a crescendo which makes even the stalwart Larraby cringe. What is to be done? But there is more to the call than might be supposed, for Mannering must battle a plot to dominate and destroy him.