The Mystery of Orcival

A countess is found murdered at her château at Orcival, everything at the scene tells a clear story, and Monsieur Lecoq's mentor reads the room in an hour - which is how the reader learns that a scene can be composed like a sentence. Gaboriau built the French detective novel out of the police gazettes; this 1867 book contains the first staged crime scene in fiction, and everything since owes it.