By the Pricking of My Thumbs — Agatha Christie

Tommy and Tuppence Beresford, Agatha Christie’s delightful sleuthing duo, investigate the strange and troubling doings behind the scenes at a gothic British nursing home in By the Pricking of My Thumbs

When Tommy and Tuppence visit an elderly aunt in her gothic nursing home, they think nothing of her mistrust of the doctors; after all, Ada is a very difficult old lady.

But when Mrs. Lockett mentions a poisoned mushroom stew and Mrs. Lancaster talks about "something behind the fireplace," Tommy and Tuppence find themselves caught up in a spine-chilling adventure that could spell death for either of them.