It is Christmas Eve. Rodolfo, a poet, and Marcello, a painter, are freezing in their studio. Marcello is painting The Crossing of the Red Sea. Colline, a philosopher, arrives as the fire Rodolfo has lit with one of his manuscripts, flickers and dies. Schaunard brings reinforcements – food, wine and fuel for the fire, bought with unexpected money from his earnings as a musician.
A knock at the door and Benoit, the landlord, arrives demanding the rent. The four Bohemians ply him with wine and then bundle him off. Marcello, Colline and Schaunard go off to join the celebrations at the Café Momus. Promising to join them soon, Rodolfo settles down to finish an article he is writing.
There is another knock. This time it is a neighbour, Mimì – a beautiful young seamstress, holding her key and an unlit candle. She begs a light and Rodolfo obliges. Mimì departs and drops her key. Together they search for the key, and their hands touch. They tell each other about themselves and Rodolfo passionately declares his love. The new lovers then set off into the night to join the others.
The square in which the Café Momus is situated is the Bohemians’ favourite haunt, bustling with shoppers and hawkers. Rodolfo buys his new love a bonnet.
At the café, Marcello’s old flame, Musetta, appears with a new admirer, Alcindoro. To attract Marcello’s attention, Musetta bursts into her famous waltz song. Marcello responds and Musetta, pretending that her shoe is pinching, dispatches Alcindoro to a cobbler. She joins in the revelry with Marcello and his friends. When they depart they leave a reminder for the hapless Alcindoro on his return – a huge bill!
It is daybreak just inside a tollgate. Snow lies on the ground. Mimì emerges from the throng of workers. She is looking for Marcello at a nearby inn where he and Musetta have been living for the past month. Pale and agitated, she tells him of Rodolfo’s jealousy which has made their life together impossible.
Mimì hides as Rodolfo suddenly appears. He declares her to be unfaithful, but then confides to Marcello that Mimì is very ill and blames himself and his poverty for not being able to help her. Mimì’s sudden coughing betrays her presence and the lovers sadly decide it is best that they part.
Their parting duet is interrupted by the sounds of a fierce quarrel between Marcello and Musetta. Mimì and Rodolfo decide to stay together until spring returns.
The studio, months later. Both pairs of lovers have now parted. Mimì and Musetta have found wealthy admirers. Rodolfo and Marcello feign indifference, but neither can forget the memory of his love. Schaunard and Colline arrive with meagre food and the four sit down to a mock ‘banquet’.
While they are acting the fool, Musetta rushes in with news that Mimì is desperately ill and has asked to be brought back to Rodolfo to die. Musetta explains that the Viscount has discarded Mimì and she has been living on the streets for weeks sinking further into poverty and desperation. The Bohemians rally to the cause. Musetta pawns her earrings and Colline his beloved coat to buy medicine for Mimì.
Alone for a short time, Mimì and Rodolfo recall the past, reliving their short spell of happiness and their dreams together. Mimì, seized by a coughing fit, falls back, exhausted. When the others return, she weakly thanks them for their kindness and falls asleep.
It is Schaunard who first notices that Mimì is dead. Rodolfo is the last to realise, by seeing the truth on his friends’ faces.