An attic in Paris, December 24, evening
In their shabby attic, the painter Marcello and the poet Rodolfo complain of the cold. In order to light the stove, Rodolfo decides to sacrifice one of his manuscripts, and the two enjoy a moment of warmth before the fire fades away. Colline, their philosopher roommate, arrives having failed to sell some books. However at the moment of total despair, the fourth Bohemian, the musician Schaunard arrives triumphantly with wood, food, wine, and money. He tries to tell his friends how he succeeded in obtaining this surprising fortune, but the other three are not interested in his tales and set the table for the meal they have craved for so many days. But Schaunard will have nothing of this. On Christmas Eve they will eat out he decrees. As the four are about to leave, Benoit, their landlord, appears and pronounces just a single word: "rent". He is invited inside, offered some wine and begins to tell the four young Bohemians about his amorous adventures. And then in the name of virtue, they throw the married landlord out and escape paying the rent one more time.
Rodolfo decides to stay behind in order to finish a newspaper article while his friends promise to wait downstairs. A weak knock is heard and the neighbor Mimi enters asking Rodolfo to light her candle which has blown out on the staircase. She is very weak and faints. Rodolfo assists her and as she revives he lights her candle and she hurries out, immediately returning as the wind has blown out the candle once again. This time Rodolfo quickly blows out his own candle too and in the darkness, Mimi drops her key. She asks Rodolfo to help her find it and when he does he conceals it in his pocket and continues searching until his hand touches Mimi's hand. "Your tiny hand is frozen," says Rodolfo and in a beautiful aria tells her that he is a poet who loves life. In her own aria which follows, Mimi says that her real name is Lucia and that she does not know why everybody calls her Mimi. She tells him that she embroiders flowers for a living. The three Bohemians downstairs wonder what has happened to Rodolfo and call him to hurry. He sends them off, intending to spend the evening with Mimi inside. But she begs him to go and join his friends promising, in a very suggestive manner, a surprise for later in the evening. Rodolfo offers his arm to Mimi and they leave together singing of their love to each other.
Outside the Cafe Momus in the Latin Quarter, later that evening
It is Christmas Eve and the Latin Quarter is crowded. Children rush after the toy seller Parpignol. The Bohemians discover that there is no free table inside the Cafe Momus and so they decide to dine outside on the pavement. Colline has had his beard trimmed, Schaunard has picked up a girl and only Marcello is alone. Rodolfo buys Mimi a bonnet and introduces her to his friends. Suddenly Marcello notices his old flame Musetta walk by expensively dressed in the arm of the old yet wealthy Alcindoro and followed by footmen loaded with parcels. Musetta also notices her former lover and sits close to him trying to attract his attention. She breaks plates, makes a fuss about her meal, yet Marcello remains indifferent and begins flirting with some other girls. Musetta does not give up, climbs on one of the tables and sings her beautiful waltz-like aria in which she describes how everybody stares at her as she walks in the streets. But in between the lines she is speaking directly to Marcello asking him to stop his games and come and embrace her. Pretending that one of her shoes is pinching her feet she sends Alcindoro to get a new one and throws herself into Marcello's arms. As the six merrymakers are about to depart a waiter brings their bill, but they have no money left. Musetta adds their bill to hers and they all leave the stage happily.
Outside a tavern by the Barriere d'enfer, one of the Paris toll gates. A cold, wet February dawn Customs men are searching the peasants, milkmaids, and the workers from the suburbs who are coming into the city to work. Musetta's voice is heard from the nearby tavern. Mimi approaches looking for Marcello. She begs him to intervene on her behalf with Rodolfo as his jealousy has made their life together impossible. She hides when Rodolfo comes out of the tavern. He tells Marcello that he has had enough of Mimi and that he cannot stand her flirtations. But then he reveals the real truth: Mimi is very ill and his life of poverty will kill her, which is why they must part. Mimi overhears their conversation and for the first time actually realizes that her illness is indeed fatal. She faints and when she comes to her senses she accepts Rodolfo's decision to part, but since they cannot bear to part immediately they agree to stay together until spring. Marcello and Musetta quarrel outside the tavern, Musetta arguing that she cannot stand his jealousy and she hates lovers who behave like husbands. The bickering of the two lovers serves a perfect contrast to the peaceful and tranquil acceptance of the love of Rodolfo and Mimi who leave hand in hand.
The attic, early summer
Just as in the opening act, Marcello and Rodolfo are trying to work, but without any success. Then it was the cold air that prevented them from concentrating. Now it is the cold feeling from inside. Both are alone and while pretending to be happy neither can forget the memory of his love. Colline and Schaunard come in with some food, but this time only bread and herring. They improvise a meal, pretend to be at a ball and even fight a mock duel when Musetta bursts in telling them that Mimi is very ill but does not dare to come in. Rodolfo rushes outside and brings Mimi in, and Musetta says that as she heard Mimi was ill she searched for her all over Paris. When she finally found her, Mimi expressed one wish only, to come to and die near Rodolfo. To make her last moments easier everyone tries to satisfy Mimi's last desires. Musetta gives her earrings to Marcello and asks him to buy Mimi a warm muff. Colline goes to pawn his coat and bring a doctor. Alone with Rodolfo, Mimi recalls their first meeting, their short spell of happiness, their dreams and their love. She thanks her friends as they return and closes her eyes. As Musetta prays for Mimi's health Schaunard discovers that Mimi is dead and Marcello tries in vein to comfort Rodolfo.