The Murders in the Rue Morgue recap

In Paris, the unnamed narrator befriends the impoverished but brilliant C. Auguste Dupin. When Madame L'Espanaye and her daughter Camille are brutally killed inside an apparently locked room, witnesses report hearing one French voice and another voice no one can identify. The police arrest bank clerk Adolphe Le Bon, but Dupin studies the physical evidence instead of accepting the obvious suspect. A secretly sprung window, extraordinary strength, nonhuman hair, marks that no human hand could make, and the witnesses' contradictory impressions lead him to an escaped orangutan. Dupin lures its sailor owner to his rooms with a newspaper notice. The sailor explains that the animal entered the house with a razor, killed both women while imitating its owner's shaving, and hid the bodies in panic. Le Bon is released, and Dupin's reconstruction exposes the limits of the police inquiry.

The narrator meets C. Auguste Dupin, an impoverished French gentleman with exceptional powers of observation, and shares a secluded Paris home with him. Their attention turns to the sensational deaths of Madame L'Espanaye and her daughter Camille in a room that appeared locked from within. Witnesses agree that they heard a Frenchman and a second speaker, yet each assigns the strange voice to a different foreign language. The victims' injuries require tremendous force, valuables remain behind, and the known exits appear impossible. Police arrest bank clerk Adolphe Le Bon because he recently delivered gold to the women. Dupin inspects the scene and finds that one window could close itself by a spring; its broken nail only made it seem secured. Hair, hand marks, agility, and the unrecognizable voice point not to a foreign murderer but to an orangutan. He places an advertisement designed to summon the animal's owner. A sailor then confesses that his orangutan escaped carrying a razor, climbed into the house, and killed the women while imitating shaving. When threatened with a whip, it panicked, thrust Camille up the chimney, threw Madame L'Espanaye through the window, and fled. The sailor later recovers the animal, Le Bon is released, and Dupin has solved the case by explaining evidence the police treated as contradictions.

Dupin's reconstruction is confirmed when the sailor admits that he brought an orangutan home from Borneo and had been trying to contain it. After watching its owner shave, the animal escaped with a razor and entered the L'Espanaye house by climbing a lightning rod. Its attempt to imitate shaving turned violent: it killed Madame L'Espanaye with the blade and strangled Camille. Frightened when the sailor appeared at the window and threatened it with a whip, the orangutan tried to conceal the bodies, forcing Camille's corpse up the chimney and throwing her mother through the window. Its escape left the room apparently sealed because the window's spring closed automatically while a broken nail made the fastening look intact. The sailor eventually recaptures and sells the animal. The authorities release Adolphe Le Bon, while the police prefect resents Dupin's success and Dupin dismisses the prefect's habit of confusing procedural activity with genuine analysis.