Three damned souls, Garcin, Inez, and Estelle are brought to the same room in hell by a mysterious Valet. They had all expected medieval torture devices to punish them for eternity, but instead find a plain room furnished in Second Empire style. None of them will admit the reason for their damnation: Garcin says that he was executed for being a pacifist, while Estelle insists that a mistake has been made.
Inez however, demands that they all stop lying to themselves and confess to their crimes. She refuses to believe that they all ended up in the room by accident and soon realizes that they have been placed together to make each other miserable. Garcin suggests that they try to leave each other alone, but Inez starts to sing about an execution and Estelle wants to find a mirror. Inez tries to seduce Estelle by offering to be her "mirror" and tell her everything she sees, but ends up frightening her instead.
After arguing they decide to confess to their crimes so they know what to expect from each other. Garcin cheated and mistreated his wife; Inez seduced her cousin’s wife while living with them; and Estelle cheated on her husband and drowned her illegitimate baby. Despite their revelations they continue to get on each other’s nerves. Garcin finally gives in to Estelle’s attempts to seduce him, driving Inez crazy. He begs Estelle to tell him he is not a coward for attempting to flee his country during wartime. When Inez tells him that Estelle is just agreeing with him so she can be with a man, Garcin tries to escape. The door suddenly opens, but he is unable to leave. He says that he will not be saved until Inez has faith in him. She refuses, promising to make him miserable forever. Forgetting that they are all dead, Estelle unsuccessfully tries to kill Inez, stabbing her repeatedly. Shocked at the absurdity of his fate, Garcin concludes, "hell is other people."