This is a novel of classical detection in a cheerful vein, though its people are real and its events plausible.

It is narrated by Tessa Price (Tessa Crichton of Death in the Grand Manor has now married Robin Price of the Metropolitan C.I.D.) and the root of the plot is blackmail. Information from her husband, and from some curious acquaintances out of her own past who are evidently connected with the case, leads Tessa herself to become (rather willingly) involved; and being almost as shrewd as she is mischievous she begins to draw various conclusions, not all of them correct.

Many of the encounters in the story take place during Tessa's visits to a London department store, on the top floor of which is a bar to which any customer who spends over twenty-five pounds is invited for a drink. Here lies part of the secret which, in its overt and practised form, is bedevilling Robin at Scotland Yard - who hates blackmailers more than any other criminals.

Tessa gets a bit too knowing, and it is her own life that is finally at stake.