Partners in Crime US First Edition Jacket 1929.jpg|thumb|140px|right]]
Partners in Crime US First Edition Jacket 1929

Six years have passed since the Beresfords began their sleuthing partnership in The Secret Adversary. Tommy now has a desk job with the British Secret Service, and Tuppence, much to her displeasure is at home, though when the Chief of British Intelligence asks them to take over the International Detective Agency, both jump at the chance of new adventures.

The fifteen stories contain parodies of fictional detectives who were well-known to readers of the 1920s. In each story Tommy and Tuppence assume the mannerisms and methods of a different detective or detective team, including Sherlock Holmes.

The stories were published together in 1929. The entire book was adapted in 1953 starring Sir Richard Attenborough and his wife Sheila Sim as Tommy and Tuppence. Ten of the stories were adapted by LWT in 1984 and starred James Warwick and Francesca Annis.

The Beresfords' old friend, Mr. Carter (who works for an unnamed government intelligence agency) arrives bearing a proposition for the adventurous duo. They are to take over 'The International Detective Agency', a recently cleaned out spy stronghold, and pose as the owners so as to intercept any enemy messages coming through. But until such a message arrives, Tommy and Tuppence are to do with the detective agency as they please - an opportunity that delights the young couple. They employ the hapless but well-meaning Albert, a young man also introduced in The Secret Adversary, as their assistant at the agency.

Eager and willing, the two set out to tackle several cases. In each case mimicking the style of a famous fictional detective of the period, including Sherlock Holmes and Christie's own Hercule Poirot.

At the end of the book, Tuppence reveals that she is pregnant, and as a result will play a diminished role in the spy business.

The stories and their detective parodies