By the Pricking of My Thumbs is a work of detective fiction by Agatha Christie and first published in the UK by the Collins Crime Club in November 1968 and in the US by Dodd, Mead and Company later in the same year. The UK edition retailed at twenty-one shillings (21/-) and the US edition at $4.95. It features her detectives Tommy and Tuppence Beresford.

Tommy and Tuppence are two fictional detectives, recurring characters in the work of Agatha Christie. Their full names are Thomas Beresford and his wife Prudence . Tommy and Tuppence first appeared in Christie's The Secret Adversary (1922). They started out their career in search of adventure and money, and the detecting life soon proved profitable and very exciting.