Published in January 1922, The Secret Adversary is the second detective fiction novel by British crime novelist Agatha Christie. The book introduces the characters of Tommy Beresford and Prudence Tuppence Cowley, two out-of-work twenty-somethings in post-war London. The two agree to form The Young Adventurers, Ltd, hiring themselves out with the slogan no reasonable offer refused. They are quickly enlisted to solve the mysterious disappearance of a young woman who was entrusted with sensitive diplomatic documents amid the sinking of the RMS Lusitania. Reviewed positively at the time of its release, the story maintains its gripping suspense until the very end.