The Secret Adversary by Agatha Christie. Tommy and Tuppence, two young people short of money and restless for excitement, embark on a daring business scheme – Young Adventurers Ltd. Their advertisement says they are ‘willing to do anything, go anywhere’. But their first assignment, for the sinister Mr Whittington, plunges them into more danger than they ever imagined. The Secret Adversary is the second published detective fiction novel by British writer Agatha Christie, first published in January 1922 in the United Kingdom by The Bodley Head and in the United States by Dodd, Mead and Company later in that same year. The book introduces the characters of Tommy and Tuppence who feature in three other Christie novels and one collection of short stories.