Following their successful first outing, Tommy and Tuppence featured in a number of Agatha Christie’s short stories. Christie drew these together and lightly revised them to produce the second novel in the series. Although a collection of stories, there is a frame narrative to give the collection coherence.

As Tommy and Tuppence settle into their role of running Theodore Blunt’s International Detective Agency, they make use of a library of “Classics”—by which is meant “classics” of detective fiction—to investigate their cases. As the episodes unfold, the couple model their investigations on the manner of—among others— Sherlock Holmes , Dr. Thorndyke , Inspector French , and even Christie’s own Hercule Poirot .

Christie recounts these early adventures of Tommy and Tuppence with a light touch, not neglecting the relationship of the husband and wife team of sleuths along the way.