A bourgeois couple, François and Simone Thévenot, accompany François's colleague Don Rafael Acosta, the ambassador from the South American nation of Miranda, and Simone's sister Florence, to the house of the Sénéchals, the hosts of a dinner party. Once they arrive, Alice Sénéchal is surprised to see them and explains that she expected them the following evening and has no dinner prepared. The would-be guests then invite Alice to join them for dinner at a nearby inn.

Arriving at the inn, the party finds it locked. They knock and are reluctantly invited in by a waitress who mentions that the restaurant is under new management. Inside, there are no diners, and the prices on the menu are disconcertingly low. The party hears wailing from an adjoining room and discovers a vigil for the corpse of the manager, who died a few hours earlier. The party is told that the coroner is coming soon, but they hurriedly depart.

Later, at the Embassy of Miranda, Acosta meets with François and Alice's husband Henri to discuss the proceeds of a large cocaine deal. During the meeting, Acosta sees a young woman selling clockwork-animal toys on the footpath outside the embassy. He shoots one of the toys with a rifle and the woman runs off. He explains that she is part of a Maoist Mirandan terrorist group that's been targeting him for months.

Two days later, the bourgeois friends attempt to have lunch at the Sénéchals', but Henri and his wife escape to the garden to have sex instead of joining them. One of the friends take their unexplained absence to mean that the Sénéchals know the police are coming and have left to avoid arrest for their involvement in drug trafficking. The party again leaves in a panic.

When the Sénéchals return from the garden, their friends are gone, but they meet a bishop who has donned their gardener's clothing. They throw him out, but when he returns wearing his bishop's robes, they embrace him with deference. The bishop asks to work for them as their gardener. He tells them about his childhood — that his parents were murdered by arsenic poisoning and that the culprit was never apprehended. (Later in the film, he goes to visit a dying man who turns out to be his parents' murderer; after blessing the man, the bishop kills him with a shotgun.)

The women visit a teahouse just as it has run out of all beverages – tea, coffee, and milk – although it finally transpires that they do have water. While they are waiting, a soldier tells them about his childhood: how after his mother's death his cold-hearted father sent him to military school. The ghost of the soldier's mother informed him that the man was not his real father but his father's killer; they had dueled over his mother. Following the ghost's request, the soldier killed the culprit with poison.

Simone meets Acosta at his apartment. They are having an affair but are interrupted by a visit from her husband, whereupon she makes a convenient excuse and leaves with him. Acosta is next visited by the same terrorist from earlier, who has come to kill him. He ambushes and chastises her, then tells her to leave when she refuses his sexual advances; his agents capture her and take her away.

Several abortive dinner parties ensue; interruptions include the arrival of a group of army officers and enlisted men, who join the dinner only to be called away for alarmingly close military maneuvers, the colonel inviting everyone to his house, only for the revelation that the colonel's dining-room is a stage set in a theatrical performance for an audience that is angry with the actors for not knowing their lines (which turns out to be Henri's dream; which then they later go to the colonel's dinner party, and it's all normal). At the colonel's party, the ambassadors gets grilled about his policies in Miranda by everyone there, which leads to the ambassador's shooting of the colonel after he insults the nation of Miranda and slaps the ambassador (which turns out to be the dream of François). The priest/gardener goes to the house of a dying man, which is the man that killed his family. After he confesses to the murder, the priest shoots his with a sniper rifle. At Alice and Henri's place, they are arrested, to improve the police's public image. During this time, the police electrocute a man by placing him in a piano. The friends are then released by the ghost of the solider's dead dad. The police chief wakes up from the dream that the friends are getting released, and they're actually released by the Interior Minister calling. The film ends with them having dinner at Henri and Alice's house again, where they get their summary execution by the terrorists, who just break into their house. And that is all a dream by Raphael, the ambassador. Most if not all of these scenes turn out to be dream sequences in which ghosts make frequent appearances.

A recurring scene throughout the film, of the six people walking silently and purposefully on a long, isolated country road, is also the final sequence.