Marcello, a painter, and Rodolfo, a writer, work on their respective pursuits in an ill-heated attic atelier. Marcello complains of the cold and of the cold-heartedness of his ex-mistress, Musetta. Rodolfo offers to warm the room by burning his manuscript. Colline, a philosopher, blusters in – no pawnshop will take his books on Christmas Eve. Schaunard, a musician, suddenly bursts into the room with much-needed food, wine and firewood. He relates the story of an eccentric nobleman who hired him to play his violin until his parrot died. After three long days, Schaunard was able to collect his fee only by feeding the bird some poisoned parsley.
Schaunard advises them to save the food for later – Christmas Eve should be celebrated with dinner at the Café Momus. While dividing the remaining money, they are interrupted by the insistent knocking of Benoit, who demands payment of the rent, long past due. The Bohemians invite him in and after priming him with wine, get the old man to admit he has a young mistress. Shocked to discover he also has a wife, the four men pretend to be horrified and quickly usher him out of the room. As the others leave for the café, Rodolfo stays behind to finish an article. He promises to catch up with them later.
Hearing another knock at the door, Rodolfo is surprised to find an attractive young woman, a neighbor whose candle needs a light. He notices her harsh cough and pale complexion, and she soon faints in his arms. Once revived, she prepares to leave only to find her key is missing. A draft puts the room into total darkness, and together they begin to hunt for the key. Rodolfo silently pockets the key and suggests they wait for the moonlight to aid their search. He takes a moment to describe himself – a poor poet, rich only in his dreams and visions, who has now found love in the eyes of a stranger.
Her name is Mimì, she says, a seamstress, who in her little room, embroiders flowers that are her private symbols of love and springtime. Life’s fairest flower is love, and she returns his adoring affection. Rodolfo’s friends call from the street, and he tells them to hold two seats at the café.
The Latin Quarter bustles with shoppers and vendors on Christmas Eve. Schaunard examines some musical instruments, Colline buys a rare book and Rodolfo buys Mimì a bonnet. Parpignol appears and dazzles the young children with toys. The Bohemians gather at the Café Momus as planned and soon after, Musetta appears in the company of Alcindoro, her wealthy, aging admirer. Trying to catch Marcello’s jealous eye, she openly describes herself as alluring to all men. In a ruse to distract Alcindoro, she pretends her shoe hurts and sends him off to the cobbler. Once reunited with Marcello, Musetta and the other Bohemians escape the café amidst a military band, assuring the waiter that Alcindoro will pick up the tab when he returns.
On a dreary winter morning, Mimì appears at the Barrière d’Enfer (“Hell’s gate”) bordering the edge of the city. She approaches the tavern where Marcello and Musetta are living, he by painting and she by singing. Mimì asks for his help – Rodolfo has become insanely and unjustifiably jealous. After cruelly demanding that she find another lover, he stormed out the night before. Marcello assures her that he is inside and promises to talk to him. The sound of his voice puts Mimì into hiding. When interrogated, Rodolfo reveals the real reason for the split – Mimì’s health is getting worse, and the squalid conditions of his apartment will only hasten her illness. Mimì’s coughing betrays her hiding place, and Rodolfo rushes to her. Marcello hears Musetta flirting with a stranger and angrily goes inside. Mimì bids Rodolfo adieu, but listening to Marcello and Musetta fight, they agree to stay together until spring.
Months later, Marcello and Rodolfo are again at work in the garret, having broken off with their respective mistresses. Neither can concentrate, however, as their thoughts are consumed by the women. Colline and Schaunard arrive with lunch, and the four make a mockery of the meager offering by pretending it is a lavish banquet. At the height of their merriment, Musetta bursts in with news that Mimì has collapsed on the stairs. Musetta found her alone, almost dead. Her dying wish is to see Rodolfo one last time. Her hands are cold, and Mimì asks for a muff. Musetta takes off her earrings and tells Marcello to sell them for medicine and to find a doctor. She leaves with him to fetch the muff. Colline takes off his beloved coat, and preparing to pawn it, he and Schaunard leave the lovers alone. Mimì admits she still loves Rodolfo, and the two reminisce about their happy past.