Analytical abilities are not peculiar to every mind and are inaccessible to analysis. To this conclusion comes the Narrator, having met in Paris in the summer of 18 .. with some Auguste Dupin, a descendant of an impoverished noble family, who astonished him at the first meeting with vast erudition and fresh imagination.
Young people quickly become friends and settle down together. The narrator has to adapt to the unusual nature and habits of Dupin – the passion for night walks and psychological analysis. A new friend amazes him by his ability to penetrate the intimate thoughts of the interlocutor, using what Dupin calls his “method” – in small external appearances he builds a complex chain of inferences.
One day friends, opening an evening newspaper, stumble upon a message about an unheard of crime. Tonight, the peaceful sleep of ordinary people living in the area of Morg Street broke heart-rending cries. They came from the house of Madame L’Espana, where she lived with her unmarried daughter Camilla. When the bedroom door was broken, people retreated in horror – the furniture was broken, gray hair of long hair stuck to the floor. Later in the chimney discovered the mutilated corpse of Camilla, and the body of Madame L’Espana was found in the courtyard. Her head was cut off with a razor.
All the witnesses agreed that when the door was broken open, the criminals were still in the bedroom. One voice clearly belonged to the Frenchman – everyone could hear the curse pronounced in French. The nationality of the second remained unknown: each of the witnesses believed that he spoke in some foreign language, agreeing that the voice was terribly rude.
The next day the newspapers brought news of the arrest of Adolf Lebon, who delivered four thousand francs from the bank... on the eve of the murder of Madame L’Espanae. It was at this stage that Dupin began to show interest in such an intricate business. Having received permission from the prefect police to inspect the scene of the crime, the friends go to Morgue Street, where Dupin is carefully examining everything.
Using his method, Dupin focuses on three circumstances: the peculiar, “inhuman” voice of one of the criminals, the unusual dexterity that was required to climb through the lightning rod, and, finally, the lack of an incentive: gold from the bank was found in the room untouched. In addition, the criminals had incredible power, once they managed to push the body into the pipe, and from the bottom up. Extracted from the compressed hands of Madame L’Espagne, the hairs and fingerprints on her neck convinced Dupin that only a giant monkey could be a killer.
Dupin advertises about the capture of a large monkey, promising to return it to the owner for a small reward. As Dupin supposed, soon a sailor from a merchant ship announced to them. Realizing that Dupin knows everything, the sailor tells the true story. Orangutan he caught on Borneo and with great torment – because of the ferocious temper of the monkey – was brought to Paris, hoping to sell it profitable. On that ill-fated night the monkey ran away, the sailor chased after her, but did not catch it and was a witness of how the beast climbed into the women’s bedroom. When the sailor scrambled with difficulty over the same lightning rod, everything was already over. Having issued a frightened exclamation, the sailor moved down…
The prefect could not hide his disappointment that the police were too drugged to do this confusing business, but after Dupin’s story, grumbling, Lebo let down in peace.