The action takes place in Paris around 1830. The young poet Rodolfo and the painter Marcello are spending Christmas Eve in the freezing garret where they live. They are joined by friends, the philosopher Colline and the musician Schaunard, who has managed to procure food, wine, and firewood: the four of them improvise a party, which is however suddenly interrupted by the arrival of the landlord to demand the rent; having invented an excuse to get rid of him without paying him, Marcello, Colline and Schaunard decide to go out to dine at Café Momus, while Rodolfo stays at home: he will join them when he had finished an article. There is a knock at the door: it is his neighbor Mimi, a young seamstress who has come to ask for a match. She is exhausted and Rodolfo revives her with some wine, but in the meantime she has lost her key. The candle goes out, and while they are searching for the key in the dark their hands touch. Mutual attraction is immediate: they tell each other about themselves and go off to join his friends.