Colline, the philosopher, enters freezing cold. Schaunard too appears carrying food, wine and firewood bundle. The friends set the table. There is a knock at the door. It’s Benoit, the landlord, who arrives to collect the overdue rent. The clever friends fool him and, after making him drunk with wine, throw him out and get ready to party at Momus Café. Only Rodolfo remains at home in order to finish writing an article. Suddenly a knock at the door is heard. It is Mimì, the neighbor. A sudden breeze of air makes her candle blow out and she is overcome with faintness. After lighting the candle again she would like to go back home but turns around because she drops her key. Her candle goes out once again in the draught. Rodolfo’s candle goes out too. In the dark he finds the key and puts it in his pocket. He tells her of his life as a poet and asks her to tell him more about herself. The description of her lonely and simple life moves the young man deeply. He declares his love to Mimì and feels that she loves him too. The voices of his friends from the courtyard are heard. Rodolfo and Mimì, full of joy, hurry up and join them.
In the Latin Quarter. On the night of Christmas Eve. A great crowd doing this and doing that on the streets and in the squares. Children happily surround the toy seller with great excitement. Rodolfo introduces Mimì to his friends and, laughing and joking, they all sit around the table at Café Momus. In the middle of their conversation Musetta, formerly Marcello's sweetheart, arrives with her rich and elderly admirer, Alcindoro. Musetta, who still loves Marcello, left him because she was fed up with her previous poor life. Marcello wants revenge on the unfaithful woman and pretends not to notice her. His indifference makes her angry but the presence of Alcindor disturbs her. She comes up with a plan to get rid of Alcindoro for a bit: she sends him to the shoemaker to buy her a pair of shoes. Musetta cheerfully falls into Marcello’s arms. A waiter approaches them with the bill, but the friends do not have enough money to pay it. Musetta finds a way out: “The old Gentleman, who went away, will pay you when he comes back!”
At the Barrière d’Enfer toll gates. It's February, early morning. Musetta teaches music. Marcello paints signs. Mimì appears, weakened and sick, looking for Rodolfo. She complains with Marcello about her lover’s terrible jealousy. Mimì is persistently coughing when she talks. She hides when she sees Rodolfo coming. Rodolfo talks with Marcello about Mimì: at first he complains her coquettishness but finally he reveals him the sad truth: “Mimì is severely being consumed by tuberculosis”. Mimì's violent weaping reveals her presence. Aware of her dramatic situation Mimì decides to leave him. In a very sad mood they say goodbye holding each other. Also for Marcello and Musetta happiness doesn’t last for long because they fiercely quarrel all the time about Musetta's flirtatiousness. Musetta leaves Marcello and Mimì, silently leaving Rodolfo, decides to part from him definitely in spring.
Marcello and Rodolfo in their attic try again to work but in vain. They miss their sweethearts. Schaunard and Colline appear carrying food. For a while the friends look cheer and carefree. Suddenly Musetta enters shouting: “Here is Mimì!”. The poor sick girl feels so bad that she isn’t able to climb up the stairs. The friends, very worried, bring her into the room. Musetta decides to sell her earrings to buy her medicines and Schaunard sells his beloved raincoat to call a doctor. All, except Rodolfo, leave the room. Mimì is glowing. Rodolfo and Mimì remember the first time they met and suddenly happiness is back! But Mimì is on the clock. She is just in time to receive from the hands of Musetta, who is running to her, a warm muff to warm up her hands and silently expires. Rodolfo cries in deep sorrow and the old friends, in front of the death, are gathering again.