The Adventure of the Sinister Stranger, by Agatha Christie (epub/Kindle)

“The Adventure of the Sinister Stranger,” the second in a series of 12 mystery stories featuring Tommy & Tuppence, was originally published in the The Sketch on October 22, 1924. These tales were billed “Tommy and Tuppence—A Detective Series by Agatha Christie” and would later be collected as Partners in Crime. “The Adventure of the Sinister Stranger,” would become the sixth story in the collection.

The conceit of the series is simple: The Beresfords’ friend Mr Carter, who works for a 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. In the meantime Tommy and Tuppence can take on cases as this detective agency, an opportunity that delights the young couple. They employ Albert, a young man introduced in The Secret Adversary, as their assistant at the agency.

The two tackle a series of cases, each mimicking the style of a famous fictional detective of the period, including Sherlock Holmes, Dr. Thorndyke, G.K. Chesterton, A.E.W. Mason, and even Christie’s own Hercule Poirot (among others). “The Adventure of the Sinister Stranger” is an espionage story, following in the footsteps of Valentine Williams and the detective brothers Francis and Desmond Okewood. One of Williams’ books in particular—The Man with the Clubfoot (1918)—is mentioned by Tuppence in the story.