Paris, the 1830s. In their Latin Quarter garret, the near-destitute painter Marcello and poet Rodolfo try to keep warm on Christmas Eve by feeding the stove with pages from Rodolfo’s latest drama. They are soon joined by their roommates—Colline, a philosopher, and Schaunard, a musician, who brings food, fuel, and funds he has collected from an eccentric student. When the landlord, Benoit, comes to collect the rent, they ply the older man with wine, then throw him out. As his friends leave for the Café Momus, Rodolfo promises to join them later, remaining behind to write. There is a knock at the door; the visitor is a pretty neighbor, Mimì, whose candle has gone out on the stairway. Rodolfo relights it. Mimì realizes she has lost her key, and in the confusion, both candles are blown out. As the two search for the key in the moonlight, their hands meet. Rodolfo tells Mimì his dreams (“Che gelida manina”). She then recounts her life alone in a lofty garret, embroidering flowers and waiting for the spring (“Mi chiamano Mimì”). Rodolfo’s friends are heard outside, urging him to join them; he calls back that he is not alone and will be along shortly. Expressing their joy in finding each other (Duet: “O soave fanciulla”), Mimì and Rodolfo embrace and leave for the café.
At the Café Momus, Rodolfo introduces Mimì to his friends. Marcello’s former sweetheart, Musetta, makes a noisy entrance on the arm of the elderly but wealthy Alcindoro. The ensuing tumult reaches its peak when, trying to regain Marcello’s attention, she sings a waltz about her popularity (“Quando me’n vo’”). Sending Alcindoro off on an errand, she falls into Marcello’s arms and tells the waiter to charge everything to Alcindoro. Soldiers march by the café, and the bohemians fall in behind.
At dawn by a tavern on the snowy outskirts of Paris, a customs official admits farm women to the city. Mimì wanders in, searching for the place where Marcello and Musetta now live. When the painter emerges, she tells him of her distress over Rodolfo’s incessant jealousy (Duet: “O buon Marcello, aiuto!”). She says she believes it is best that they part. When Rodolfo appears from the tavern, Mimì hides nearby, though Marcello thinks she has gone. The poet tells Marcello that he wants to separate from his sweetheart, citing her fickleness; pressed for the real reason, he breaks down, saying that her coughing can only grow worse in the poverty they share; he’s desperately afraid she will die from her illness. Overcome with tears, Mimì stumbles forward to bid her lover farewell (“Donde lieta uscì”). While Mimì and Rodolfo recall past happiness, Musetta quarrels with Marcello, who has caught her flirting (Quartet: “Addio dolce svegliare”). The painter and his mistress part, hurling insults at each other, but Mimì and Rodolfo decide to remain together until spring.
Now separated from their girlfriends, Rodolfo and Marcello lament their loneliness in the garret (Duet: “O Mimì, tu più non torni”). Colline and Schaunard bring a meager meal. To lighten their spirits the four stage a dance, when suddenly Musetta bursts in to tell them that Mimì is outside, too weak to come upstairs. Rodolfo carries her in, while Musetta asks Marcello to sell her earrings for medicine and Colline goes off to pawn his overcoat (“Vecchia zimarra”). Left alone, Mimì and Rodolfo recall their first meeting and their happy days, but she is seized with violent coughing (Duet: “Sono andati?”). The others return and Mimì drifts into unconsciousness. When Rodolfo at last realizes that she is dead, he throws himself despairingly on her body, calling her name.