The Secret Adversary

The Secret Adversary Agatha Christie - 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[1] and in the United States by Dodd, Mead and Company later in that same year. Hiring themselves out as "young adventurers willing to do anything" is a smart move for Tommy and Tuppence.
All Tuppence has to do is take an all-expenses-paid trip to Paris and pose as someone named Jane Finn. But with the job comes a threat to her life, and the disappearance of her mysterious employer. Now Tuppence's newest job is playing detective-because if there's a Jane Finn that really exists, she's got a secret that's putting both their lives in danger.