Plot is the exposition, rising action, climax, falling action, and denouement of a story.

The exposition of “Murders in the Rue Morgue” is when the narrator and Dupin read of the deaths of Madame L'Espanaye and Camille L'Espanaye in the newspaper.

The rising action is when Adolphe de Bon is arrested. This is when Dupin feels obligated to help solve the case because of favors he owes de Bon. Dupin and the narrator then visit the L’Espanaye apartment to search for clues.

The climax occurs when Dupin places an "Ourang-Outang Found" ad in a local paper popular with sailors. Dupin knows the sailor is not the murderer, but knows he will be able to prove who the murderer is.

The falling action is when Dupin explains his thought process in accusing the orangutan of murder. Dupin pieces together little clues to solve the murder. These little clues include the hair removed from Madame L’Espanaye’s fingers and the size of the hand that killed the two women.

The denouement is when the sailor explains how the orangutan got into the fourth-story apartment. Le Bon is released from prison and the sailor sells the orangutan. Dupin feels complacent about having solving a case that had the police at standstill.