THE RED HOUSE MYSTERY is a "Whodunit" mystery novel, published in 1922. It was Milne's only mystery novel and was immediately popular; Alexander Woollcott called it "one of the three best mystery stories of all time," and Raymond Chandler, in his 1944 essay The Simple Art of Murder called it "an agreeable book, light, amusing in the Punch style, written with a deceptive smoothness that is not as easy as it looks."