Valjean arrives at the barricade and immediately saves a man's life. He is still not certain if he wants to protect Marius or kill him. Marius recognizes Valjean at first sight. Enjolras announces that they are almost out of cartridges. When Gavroche goes outside the barricade to collect more ammunition from the dead National Guardsmen, he is shot by the troops.

Valjean volunteers to execute Javert himself, and Enjolras grants permission. Valjean takes Javert out of sight, and then shoots into the air while letting him go. Marius mistakenly believes that Valjean has killed Javert. As the barricade falls, Valjean carries off the injured and unconscious Marius. All the other students are killed. Valjean escapes through the sewers, carrying Marius's body. He evades a police patrol, and reaches an exit gate but finds it locked. Thénardier emerges from the darkness. Valjean recognizes him, but his filthy appearance prevents Thénardier from recognizing him. Thinking Valjean a murderer lugging his victim's corpse, Thénardier offers to open the gate for money. As he searches Valjean and Marius's pockets, he surreptitiously tears off a piece of Marius's coat so he can later find out his identity. Thénardier takes the thirty francs he finds, opens the gate, and allows Valjean to leave, expecting Valjean's emergence from the sewer will distract the police who have been pursuing him.

Upon exiting, Valjean encounters Javert and requests time to return Marius to his family before surrendering to him. Javert agrees, assuming that Marius will be dead within minutes. After leaving Marius at his grandfather's house, Valjean asks to be allowed a brief visit to his own home, and Javert agrees. There, Javert tells Valjean he will wait for him in the street, but when Valjean scans the street from the landing window he finds Javert has gone. Javert walks down the street, realizing that he is caught between his strict belief in the law and the mercy Valjean has shown him. He feels he can no longer give Valjean up to the authorities but also cannot ignore his duty to the law. Unable to cope with this dilemma, Javert commits suicide by throwing himself into the Seine.

Marius slowly recovers from his injuries. As he and Cosette make wedding preparations, Valjean endows them with a fortune of nearly 600,000 francs. As their wedding party winds through Paris during Mardi Gras festivities, Valjean is spotted by Thénardier, who then orders Azelma to follow him. After the wedding, Valjean confesses to Marius that he is an ex-convict. Marius is horrified, assumes the worst about Valjean's moral character, and contrives to limit Valjean's time with Cosette. Valjean accedes to Marius' judgment and his separation from Cosette. Valjean loses the will to live and retires to his bed.

Thénardier approaches Marius in disguise, but Marius recognizes him. Thénardier attempts to blackmail Marius with what he knows of Valjean, but in doing so, he inadvertently corrects Marius's misconceptions about Valjean and reveals all of the good he has done. He tries to convince Marius that Valjean is actually a murderer, and presents the piece of coat he tore off as evidence. Stunned, Marius recognizes the fabric as part of his own coat and realizes that it was Valjean who rescued him from the barricade. Marius pulls out a fistful of notes and flings it at Thénardier's face. He then confronts Thénardier with his crimes and offers him an immense sum to depart and never return. Thénardier accepts the offer, and he and Azelma travel to America where he becomes a slave trader.

As they rush to Valjean's house, Marius tells Cosette that Valjean saved his life at the barricade. They arrive to find Valjean near death and reconcile with him. Valjean tells Cosette her mother's story and name. He dies content and is buried beneath a blank slab in Père Lachaise Cemetery.