It’s Christmas Eve.
Marcello, a painter, is trying to work in the extreme cold of a studio he shares with Rodolfo, a writer. Rodolfo is keeping them warm by burning the manuscript of his play when their friends arrive: Colline, a philosopher and Schaunard, a musician, who is in high spirits having unexpectedly come into some money that will help the friends get through the winter.
Their landlord Benoit arrives, demanding rent. They manage to avoid paying Benoit and set off to Café Momus to celebrate their good fortune. Rodolfo decides to stay at the studio for a little longer to finish an article when Mimì, a neighbour, knocks on his door. Her candle has gone out and she needs a new flame. Mimì is feeling weak, and she faints. As she comes round, she realises she dropped her key. Rodolfo helps her to look for the key, and in the darkness, their hands touch.
From the street below, Rodolfo’s friends call out for him to hurry up; he promises to join them with Mimì.
Outside Café Momus, the streets are bustling with last-minute Christmas shoppers. Rodolfo buys Mimì a pink beret, and then takes her to meet his friends.
Marcello loses his temper when his old flame, Musetta, walks by with Alcindoro, her wealthy companion, and his pretence of ignoring her drives her to make an outrageous scene.
Finally, Musetta despatches Alcindoro to buy her a pair of shoes and throws herself into Marcello’s arms. The waiter arrives with the bill. Musetta instructs the Bohemians to add their bill to hers so that Alcindoro can settle them both.
It is now February. Mimì asks Marcello to speak to Rodolfo for her because his jealousy has made their life together impossible. She then overhears the men talking about her: Rodolfo believes she is so ill that her only chance of recovery is to leave him and his life of poverty. Marcello and Musetta quarrel while Rodolfo and Mimì confront the necessity of separation.
Later in spring, Marcello and Rodolfo are trying to work, though their thoughts stray to their absent lovers. Schaunard and Colline bring some meagre food and the four friends pretend that they are enjoying a fine dinner party with dancing. They are interrupted when Musetta bursts in to say that Mimì is dying. She wants to be with Rodolfo. The friends do what they can but it is too late to save her.