Dead End in Mayfair — Leonard Gribble

In another Yard case for Commander Anthony Slade, there is blackmail at London's latest night spot. Ruth Graham, a journalist, and Stephen Blaine, a blackmail victim, pit their wits against unusual odds when sudden violence erupts. Then Slade has to direct the "Met" in a gruelling bout of police work, which involves a drugs gang and a titled master-mind who has developed blackmail into a lucrative practice. The climax to the case is both startling and brutal.