A quandary for John Mannering (aka ‘The Baron’). A young brash artist is found half-dead, with a noose around his neck, on the same day he had attempted to get Mannering to finance his career. The artist's terrified girlfriend desperately seeks help. Has the man tried to kill himself, or is it a case of attempted murder?

The National Gallery has high security, but a painting is nevertheless stolen. Gideon of Scotland Yard knows of only a few thieves who could pull this off. However, one turns up dead and an art dealer's daughter is kidnapped and a counterfeiting ring moves into town. Clearly, Gideon is facing something both major and mysterious . . .

John Mannering, retired jewel thief known as ‘The Baron’, is offered a set of diamonds which have been stolen from the Louvre. He faces a dangerous dilemma; the jewels may lead him to a murderer, but he is also tempted to return to his old ways. He is lead into a dangerous adventure, in which he is kidnapped and threatened with death.