Valjean escapes, is recaptured, and is sentenced to death. The king commutes his sentence to penal servitude for life. While imprisoned at the military port of Toulon, Valjean, at great personal risk, rescues a sailor caught in the ship's rigging. Spectators call for his release. Valjean fakes his own death by allowing himself to fall into the ocean. Authorities report him dead and his body lost.

Valjean arrives at Montfermeil on Christmas Eve. He finds Cosette fetching water in the woods alone and walks with her to the inn. He orders a meal and observes how the Thénardiers abuse her, while pampering their own daughters Éponine and Azelma, who mistreat Cosette for playing with their doll. Valjean leaves and returns to make Cosette a present of an expensive new doll which, after some hesitation, she happily accepts. Éponine and Azelma are envious. Madame Thénardier is furious with Valjean, while her husband makes light of Valjean's behaviour, caring only that he pay for his food and lodging.

The next morning, Valjean informs the Thénardiers that he wants to take Cosette with him. Madame Thénardier immediately accepts, while Thénardier pretends to love Cosette and be concerned for her welfare, reluctant to give her up. Valjean pays 1,500 francs to them, and he and Cosette leave the inn. Thénardier, hoping to swindle more out of Valjean, runs after them, holding the 1,500 francs, and tells Valjean he wants Cosette back. He informs Valjean that he cannot release Cosette without a note from the child's mother. Valjean hands Thénardier Fantine's letter authorizing the bearer to take Cosette. Thénardier then demands that Valjean pay a thousand crowns, but Valjean and Cosette leave. Thénardier regrets that he did not bring his gun and turns back toward home.

Valjean and Cosette flee to Paris. Valjean rents new lodgings at Gorbeau House, where he and Cosette live happily. However, Javert discovers Valjean's lodgings there a few months later. Valjean takes Cosette and they try to escape from Javert. They soon find shelter in the Petit-Picpus convent with the help of Fauchelevent, the man whom Valjean once rescued from being crushed under a cart and who has become the convent's gardener. Valjean also becomes a gardener and Cosette becomes a student at the convent school.