The Mystery of the Open Window

The Mystery of the Open Window is a 1929 mystery detective novel by Anthony Gilbert, the pen name of British writer Lucy Beatrice Malleson. It is the fourth novel in a series featuring her amateur detective, the politician Scott Egerton. Unlike the rest of the series it was published by Gollancz rather than Collins. It takes the form of a locked room mystery, a popular branch of the genre during the Golden Age of Detective Fiction.

Synopsis
By coincidence, Egerton is at a disreputable inn in Paris when the proprietor is visited by the wealthy Sir Henry Archer, owner of the famous Archer Library, carrying several valuable books with him. Obviously in a state of terror, he demands that his room be locked and his window barred. Nonetheless the following morning he is found in bed, stabbed to death.