What to Do? — John Creasey

John Mannering (aka The Baron') is an ex-cracksman, who is now straight', and also acts to solve crimes. His wife learns that Quinns, a curio shop in London's Mayfair is for sale, and urges him to buy it. His attempt to do so, however, is shrouded in mystery, and the police wonder if he has once again turned his hand to his old profession.