What was Agatha Christie's first published short-story collection?

Agatha Christie’s first published short-story collection was Poirot Investigates.

The collection was first published in the United Kingdom by The Bodley Head in March 1924. Its eleven stories follow Hercule Poirot as he tackles cases involving theft, jealousy, greed, revenge and political danger, usually with Captain Hastings and Inspector Japp nearby.

Most of the stories had appeared earlier in The Sketch magazine, beginning in 1923. The magazine’s editor, Bruce Ingram, had been impressed by Poirot in The Mysterious Affair at Styles and encouraged Christie to write more short adventures featuring him. The collection therefore helped establish Poirot as a recurring literary detective beyond his debut novel.

The American edition, published by Dodd, Mead in 1925, contained three additional stories: “The Chocolate Box,” “The Veiled Lady” and “The Lost Mine.” That difference between British and American contents sometimes creates confusion about what counts as the collection’s original story list. The later Poirot’s Early Cases was a retrospective 1974 volume, not Christie’s first collection.