The Secret Adversary is a work of detective fiction by Agatha Christie. It was first published in the UK in January 1922.The book introduces the characters of Tommy and Tuppence, who feature in three other Christie books and one collection of short stories written throughout her writing career. The Times Literary Supplement in 1922 reviewed the story as "a whirl of thrilling adventures," considering the characters Tommy and Tuppence as "refreshingly original." "It's an excellent yarn and the reader will find it as impossible as we did to put it aside until the mystery has been fathomed." - Daily Chronicle