The Red House Mystery (1922) by A.A. Milne is a classic whodunit set in an English country estate. The story begins when Mark Ablett, the owner of the Red House, is visited by his estranged brother, Robert, from Australia. Shortly after Robert's arrival, gunshots are heard, and Robert is found dead-while Mark has seemingly vanished.

An amateur sleuth, Antony Gillingham, with the help of his friend Bill, takes on the role of detective. Together, they sift through clues, alibis, and hidden secrets within the household, uncovering layers of deception. The mystery combines suspense, wit, and charm, ultimately revealing a clever solution to the crime.

It remains Milne's only detective novel, written before he became world-famous for Winnie-the-Pooh.