The Secret Adversary is a work of detective fiction by Agatha Christie. The book introduces the characters of Tommy and Tuppence who feature in three other Christie novels and one collection of short stories. Set in 1919, young couple Tommy Beresford and Tuppence Cowley form a partnership, hiring themselves out as ''young adventurers''. Their first case, however, turns out to be more of an adventure than they expected, working to find documents that, if known to the general public, would fuel a communist revolution in Britain.