The Exterminating Angel - Luis Buñuel (1962)

Edmundo and Lucia de Nobile are hosting a lavish dinner party for twenty-two following a night out at the opera, the party guests who include many from the production. One hour before dinner is to begin, the household servants, one by one, are called away or feel the need to leave the house for one reason or another. By the middle of dinner, during which the bourgeois guests cattily gossip about the others and/or talk about their own self-centered issues such as embarking on extramarital affairs, Julio, the household's chief steward, is the only servant remaining. After dinner, the guests move to the music room to continue their conversations and listen to one of the guests, Blanca, play the piano, while Julio cleans up on his own. At the time the guests would normally leave to go home at the end of the party, they all inexplicably decide to stay overnight, and although Edmundo reluctantly offers everyone bedrooms, they all end up sleeping in the music room. By morning, after a small respite, some want to stay longer, but even those who decide to leave immediately somehow feel that they can't. Slowly one by one, all twenty-three, which now includes Julio, come to the realization that for whatever reason they can't leave the music room, and by the time the outside world realizes they are trapped inside, no one can get in. They are most concerned about getting the basic necessities to survive, but as time goes on, the basic nature of each of the twenty-three begins to emerge. But they have to figure out what has caused their imprisonment if they will have any chance of ever leaving.