Rudolph and Marcel are sitting in the latter’s attic-studio in the Quartier Latin, in Paris. Marcel is absorbed in his painting. The day is cold. They have no money to buy coal. Marcel takes a chair to burn it, when Rudolph remembers that he has a manuscript which has been rejected by the publishers and lights a fire with that instead. Colline enters, looking abject and miserable. He had gone out to pawn his books, but nobody wanted them. Their friend, Schaunard, however, had better luck. He comes bringing fuel and provisions. They all prepare their meal, when the landlord enters and demands the payment of his rent. The friends offer him a glass of wine and turn him out amidst joking and laughter. After their gay repast they separate and Rudolph remains alone writing.
A knock is heard at the door and Mimi, a little seamstress, who lives on the same floor, appears and asks Rudolph to give her a match to light her candle. As she is about to go out, she falls in a faint. Rudolph gives her wine and restores her to consciousness. She tells him that she suffers from consumption. Rudolph is struck by her beauty and her delicate hands. She notices that she has lost her key and whilst they search for it their candles are extinguished. As they grope on the floor in the dark, Rudolph finds the key and puts it in his pocket. Their hands meet and Rudolph tries to warm her hands and tells her all about his life. Mimi confides her struggles to him and their conversation soon turns upon their love for each other.
Rudolph’s friends have repaired to their favorite Cafe. It is Christmas Eve and everyone is in festive spirits. All the shops are bright and displaying their goods. Hawkers offer their goods for sale in the streets. Rudolph and Mimi are seen entering a milliner’s where Rudolph is to buy her a new hat. Colline, Schaunard and Marcel take their seats in front of the Cafe, where a table has been prepared for them. Rudolph introduces Mimi to his friends. Musetta, Marcel’s flame, with whom he has quarrelled, now enters with Alcindoro. Marcel is deeply moved when he sees her. Musetta notices this and sends Alcindoro on an errand. Whilst he is away, she makes peace with Marcel. The friends find that they have not sufficient money to pay for their supper, so they carry off Musetta and leave their bills to be paid by Alcindoro.
Months have elapsed, bringing joy and misery to Rudolph and Mimi. Rudolph loves Mimi passionately, but is consumed with jealousy. On a wintry day, Marcel is seen leaving a tavern near the Gates of Paris. He meets Mimi; she looks pale and haggard. She asks Marcel to help her and tells him of Rudolph’s love and jealousy, explaining that she must leave him. Rudolph now comes upon the scene and not seeing Mimi tells of all the miseries of their lives; how he loves her and believes her to be dying of consumption. Mimi’s cough betrays her and although she says good-bye to Rudolph they find they cannot part and determine to await the spring. Meanwhile Musetta and Marcel have a violent quarrel.