First published 1942; cover shown is the 2000 Kensington Books (USA) paperback edition.
Nurse-detective Hilda Adams barely makes it home from a grueling case before she is called out on another one. This time Inspector Fuller wants her to take care of Eliza Fairbanks, the very wealthy matriarch of a family with more than its fair share of secrets.
Mrs Fairbanks has been finding bats in her bedroom, arsenic on her strawberries and rats in her cupboard. She believes a member of her family is trying to kill her, and she is so paranoid she keeps even Hilda locked out of her bedroom. But locking the door is not enough: very soon Hilda finds the old lady dead in her bed, a kitchen knife sticking out of her chest.
The room had a locked door and a sealed window. How could she have been killed, with Hilda keeping guard right outside? The hunt is on to solve a seemingly impossible murder, and to unmask a killer.
Mary Roberts Rinehart (1876 - 1958) wrote over 60 mysteries, and is credited with inventing the phrase "The butler did it", as well as the "Had-I-But-Known" subgenre (now widely ridiculed within the industry). While her mysteries are still being published, read and enjoyed, her style of writing is quite dated, especially compared with a writer such as Agatha Christie, whose novels from the same era are still fresh today.