Retired gentleman cracksman, John Mannering, (aka 'The Baron'), who runs Quinns Antiques in Mayfair, is faced with reverting to his old profession in an effort to save the life of a man accused of murder. The suspense is literally killing and even 'The Baron' is not sure of the man's innocence. He gets involved to the point where he too is in danger of being suspected as an accomplice and the reader is kept on edge right up until a very unexpected climax and solution to the mystery is revealed.