In a small room in Paris, an unnamed narrator, who also narrates “The Murders in the Rue Morgue,” sits quietly with his friend, C. Auguste Dupin. He ponders the murders in the Rue Morgue, which Dupin solved in that story. Monsieur G——, the prefect of the Paris police, arrives, having decided to consult Dupin again. The prefect presents a case that is almost too simple: a letter has been taken from the royal apartments. The police know who has taken it: the Minister D——, an important government official. According to the prefect, a young lady possessed the letter, which contains information that could harm a powerful individual. When the young lady was first reading the letter, the man whom it concerned came into the royal apartments. Not wanting to arouse his suspicion, she put it down on a table next to her. The sinister Minister D—— then walked in and noted the letter’s contents. Quickly grasping the seriousness of the situation, he produced a letter of his own that resembled the important letter. He left his own letter next to the original one as he began to talk of Parisian affairs. Finally, as he prepared to leave the apartment, he purposely retrieved the lady’s letter in place of his own. Now, the prefect explains, the Minister D—— possesses a great deal of power over the lady.
Dupin asks whether the police have searched the Minister’s residence, arguing that since the power of the letter derives from its being readily available, it must be in his apartment. The prefect responds that they have searched the Minister’s residence but have not located the letter. He recounts the search procedure, during which the police systematically searched every inch of the hotel. In addition, the letter could not be hidden on the Minister’s body because the police have searched him as well. The prefect mentions that he is willing to search long and hard because the reward offered in the case is so generous. Upon Dupin’s request, the prefect reads him a physical description of the letter. Dupin suggests that the police search again.
One month later, Dupin and the narrator are again sitting together when the prefect visits. The prefect admits that he cannot find the letter, even though the reward has increased. The prefect says that he will pay 50,000 francs to anyone who obtains the letter for him. Dupin tells him to write a check for that amount on the spot. Upon receipt of the check, Dupin hands over the letter. The prefect rushes off to return it to its rightful owner, and Dupin explains how he obtained the letter.
Dupin admits that the police are skilled investigators according to their own principles. He explains this remark by describing a young boy playing “even and odd.” In this game, each player must guess whether the number of things (usually toys) held by another player is even or odd. If the guesser is right, he gets one of the toys. If he is wrong, he loses a toy of his own. The boy whom Dupin describes plays the game well because he bases his guesses on the knowledge of his opponent. When he faces difficulty, he imitates the facial expression of his opponent, as though to understand what he thinks and feels. With this knowledge, he often guesses correctly. Dupin argues that the Paris police do not use this strategy and therefore could not find the letter: the police think only to look for a letter in places where they themselves might hide it.
Dupin argues that the Minister D—— is intelligent enough not to hide the letter in the nooks and crannies of his apartment—exactly where the police first investigate. He describes to the narrator a game of puzzles in which one player finds a name on a map and tells the other player to find it as well. Amateurs, says Dupin, pick the names with the smallest letters. According to Dupin’s logic, the hardest names to find are actually those that stretch broadly across the map because they are so obvious.
With this game in mind, Dupin recounts the visit he made to the Minister’s apartment. After surveying the Minister’s residence, Dupin notices a group of visiting cards hanging from the mantelpiece. A letter accompanies them. It has a different exterior than that previously described by the prefect, but Dupin also observes that the letter appears to have been folded back on itself. He becomes sure that it is the stolen document. In order to create a reason for returning to the apartment, he purposely leaves behind his snuffbox. When he goes back the next morning to retrieve it, he also arranges for someone to make a commotion outside the window while he is in the apartment. When the Minister rushes to the window to investigate the noise, Dupin replaces the stolen letter with a fake. He justifies his decision to leave behind another letter by predicting that the Minister will embarrass himself when he acts in reliance upon the letter he falsely believes he still possesses. Dupin remarks that the Minister once wronged him in Vienna and that he has pledged not to forget the insult. Inside the fake letter, then, Dupin inscribes, a French poem that translates into English, “So baneful a scheme, if not worthy of Atreus, is worthy of Thyestes.”
Along with “The Murders in the Rue Morgue,” “The Purloined Letter” establishes a new genre of short fiction in American literature: the detective story. Poe considered “The Purloined Letter” his best detective story, and critics have long identified the ways in which it redefines the mystery genre—it turns away from action toward intellectual analysis, for example. As opposed to the graphic violence of “The Murders in the Rue Morgue,” which features bodily mutilation and near decapitation by a wild animal, “The Purloined Letter” focuses more dryly on the relationship between the Paris police and Dupin, between the ineffectual established order and the savvy private eye. When the narrator opens the story by reflecting upon the gruesome murders in the Rue Morgue that Dupin has helped to solve, Poe makes it clear that the prior story is on his mind. Poe sets up the cool reason of “The Purloined Letter” in opposition to the violence of “The Murders in the Rue Morgue.” The battered and lacerated bodies of “The Murders in the Rue Morgue” are replaced by the bloodless, inanimate stolen letter. However, just as the Paris police are unable to solve the gory crime of passion in “The Murders in the Rue Morgue,” they are similarly unable to solve this apparently simple mystery, in which the solution is hidden in plain sight.
Poe moves away from violence and action by associating Dupin’s intelligence with his reflectiveness and his radical theories about the mind. This tale does not have the constant action of stories like “The Cask of Amontillado” or “The Black Cat.” Instead, this tale features the narrator and Dupin sitting in Dupin’s library and discussing ideas. The tale’s action, relayed by flashbacks, takes place outside the narrative frame. The narrative itself is told through dispassionate analysis. The intrusions of the prefect and his investigations of the Minister’s apartment come off as unrefined and unintellectual. Poe portrays the prefect as simultaneously the most active and the most unreflective character in the story. Dupin’s most pointed criticisms of the prefect have less to do with a personal attack than with a critique of the mode of investigation employed by the police as a whole. Dupin suggests that the police cannot think outside their own standard procedures. They are unable to place themselves in the minds of those who actually commit crimes. Dupin’s strategy of solving crimes, on the other hand, involves a process of thinking like someone else. Just as the boy playing “even and odd” enters his opponent’s mind, Dupin inhabits the consciousness of the criminal. He does not employ fancy psychological theories, but rather imitates the train of thought of his opponent. He succeeds in operating one step ahead of the police because he thinks as the Minister does.
This crime-solving technique of thinking like the criminal suggests that Dupin and the Minister are more doubles than opposites. The revenge aspect of the story, which Dupin promises after the Minister offends him in Vienna, arguably derives from their threatening similarity. Dupin’s note inside the phony letter, translated “So baneful a scheme, if not worthy of Atreus, is worthy of Thyestes,” suggests the rivalry that accompanies brotherly minds. In the French dramatist Crébillon’s early-eighteenth-century tragedy Atrée et Thyeste (or Atreus and Thyestes), Thyestes seduces the wife of his brother, Atreus. In retaliation, Atreus murders the sons of Thyestes and serves them to their father at a feast. Dupin implies here that Thyestes deserves more punishment than Atreus because he commits the original wrong. In contrast, Atreus’s revenge is legitimate because it repays the original offense. Dupin considers his own deed to be revenge and thereby morally justified.