The Mystery of the Yellow Room

Mademoiselle Stangerson is attacked by an unknown assailant, who then escapes from her locked bedroom without being seen. Joseph Rouletabille, a bright young reporter, is drawn to investigate the mystery, trying to understand what really happened (and how!) before another attempt on her life is made.
The Mystery of the Yellow Room is an early ¿locked-room mystery¿ novel, and helped define it as a genre. Agatha Christie, in her novel The Clocks, had her fictional detective Hercule Poirot describe it as a masterpiece. John Dickson Carr, frequently cited as the best mystery writer specializing in locked-room mysteries, named it as his own personal favorite example of the genre.