1920's LondonIf one more person gives Rosemary Lillywhite unwanted advice on when to stop mourning the loss of her beloved husband, she fears she will lose control of her sensibilities. All she wants is to be left alone to drown her misery in a glass of gin and tonic, but when Grace Barton knocks on the door of her dead husband's investigative office, Rosemary faces a choice: come out of hiding or turn away someone in need of help.As Grace recounts her tale of intrigue, Rosemary discovers a shared connection with the woman that has her accepting an invitation she can't refuse. With bright young thing, Vera Blackburn, by her side Rosemary trades her widow weeds for a party dress and heads to a fancy do at Barton Manor where the drinks flow freely, but there's an undercurrent of unease.The night ends in a murder for which Rosemary's brother is the prime suspect. What's worse, the handsome chief inspector on the case is a man Rosemary knows well. He was her husband's best mate, and he takes a dim view of lady detectives. Or maybe just of Rosemary becoming one.What will it take for Rosemary to solve the crime before her brother hangs for a murder he didn't commit?