Sung through, Les Misérables opens in a prison in Toulon, France in 1815, where the prisoners work at hard labour. After nineteen years of imprisonment (five for stealing bread for his starving sister and her family, and the rest for trying to escape) Jean Valjean, prisoner 24601, is released on parole by the policeman Javert. By law, Valjean must display a yellow ticket-of-leave, which condemns him as an outcast. He then meets the Bishop of Digne, who offers him food and shelter. Valjean steals silver from the bishop and the police catch him shortly. The bishop, however, lies to save Valjean and helps him begin a new life . Humbled by the bishop's mercy and kindness, Valjean decides to follow the bishop's advice and breaks his parole.

Eight years later, Valjean, having assumed a new identity as Monsieur Madeleine, is a wealthy factory owner and mayor of Montreuil-sur-Mer. One of his workers, Fantine, has a fight when the other workers discover she is sending money to her secret illegitimate child who is living with an innkeeper and his wife. The Mayor breaks up the conflict, but asks his factory foreman to resolve it. The other women demand Fantine's dismissal, and because she had previously rejected his advances, the foreman agrees and throws Fantine out. Fantine sings about her broken dreams and about the father of her daughter who abandoned her. Desperate for money, she sells her locket and her hair, before becoming a prostitute.

When she fights back against an abusive customer, Javert, now stationed in Montreuil-sur-Mer, arrests her. "Madeleine" soon arrives, and realising his part in the ruination of Fantine, he orders Javert to let her go and takes her to a hospital. Soon after, when the Mayor rescues Fauchelevant, who is pinned by a runaway cart, Javert is reminded of Jean Valjean (who was abnormally strong), whom he has sought for years for breaking parole. However, Javert assures the mayor that Valjean has been arrested recently and will be in court later in the day. Unwilling to see an innocent man go to prison in his place, Valjean confesses his identity to the court—that he is the prisoner 24601—revealing the convict's brand on his chest as proof . Before returning to prison, Valjean visits the dying Fantine and promises to find and look after her daughter Cosette.

When Javert arrives to arrest him, Valjean asks for three more days to fetch Cosette, but Javert refuses to believe his honest intentions. Valjean eventually knocks Javert out and escapes. The next scene occurs in an inn at Montfermeil run by the Thénardiers, where Cosette has been living. The Thénardiers have been abusing the little girl, while indulging their own daughter, Éponine. Cosette dreams of a better life before Madame Thénardier sends her to fetch water in the dark. As the inn fills for the evening, the Thénardiers use numerous methods to cheat their customers. Valjean finds Cosette fetching water and pays the Thénardiers fifteen hundred Francs to let him take Cosette away.

Nine years later, Paris is in upheaval because General Lamarque, the only man in the government who shows mercy to the poor, is ill and may soon die. The young street urchin Gavroche mingles with the prostitutes and beggars on the street, while students Marius Pontmercy and Enjolras discuss the likely demise of the general. A street gang led by the Thénardiers prepares to ambush Valjean, whom Thénardier recognizes as the man who took Cosette. Éponine sees Marius, whom she secretly loves, and warns him to stay away, but Marius accidentally bumps into Cosette and immediately falls in love. The Thénardiers' attempt to rob Valjean and Cosette fails, as the result of Javert, who does not recognise Valjean until after he makes his escape. Javert gazes at the night sky, comparing his hunt of Valjean and justice to the order of the stars.

Meanwhile, Marius, although he does not know Cosette's name, persuades a reluctant Éponine to help to find her. The scene shifts to a political meeting in a small café where a group of idealistic students led by Enjolras gathers to prepare for a revolution that they believe will materialise after General Lamarque's death, Marius arrives late and when Gavroche brings the news of the General's death, the students march out into the streets.

Cosette is infatuated with Marius, and although Valjean realises that his daughter has grown up, he refuses to tell her about his past or her mother. In spite of her own feelings, Éponine leads Marius to Cosette, and then prevents her father's gang from robbing Valjean's house Valjean, convinced that Javert was lurking outside his house, tells Cosette that they must prepare to flee the country. On the eve of the Paris Uprising, Valjean prepares to go into exile; Cosette and Marius part in despair of ever meeting again; Éponine mourns the loss of Marius; Marius decides to join the other students as they prepare for the upcoming conflict; Javert plans to spy on the students and learn their secrets; and the Thénardiers look forward to stealing from the corpses of those who will be killed during the battle to come.

ACT TWO

As the students begin a barricade, Javert, disguised as one of the rebels, volunteers to "spy" on the government troops. Marius notices that Éponine has disguised herself as a boy and has joined the revolutionaries. He sends her with a letter to deliver to Cosette, which will also serve to get Éponine to safety. Valjean intercepts the letter, promising Éponine he will tell Cosette about the letter. After Éponine leaves, Valjean reads the letter, learning about Marius and Cosette's relationship. While walking the streets of Paris, Éponine decides, despite what he has said to her, to rejoin Marius at the barricade.

At the barricade, the students defy an army warning them to surrender or die. Javert returns and tells the students that the government will attack, but Gavroche exposes him as a spy. Éponine is shot as she returns to the barricades and dies in Marius's arms. Valjean arrives at the barricades in search of Marius as the first battle erupts, and he saves Enjolras by shooting a sniper. As a reward, he asks to be the one to kill Javert, but instead he releases him and even gives him his address. The students settle down for a night, while Valjean prays to God to save Marius from the onslaught that is to come.

As dawn approaches, Enjolras realises that the people have abandoned them. He sends away women and fathers of children, but resolves to continue to fight. With ammunition running low during the second attack, Gavroche moves in front of the barricade to collect more cartridges. As he collects bullets and runs back behind the barricade, he is shot three times. He dies as he returns behind the barricade. Enjolras and the students realise that they will likely die. The army gives a final warning for surrender, but the rebels refuse, and as they continue to fight, they are all killed except Valjean and Marius.

Carrying a wounded Marius on his back, Valjean escapes through the sewers. Meanwhile, Thénardier is also in the sewers, stealing valuables from bodies, laughing that he is performing a "service to the town". Thénardier takes a ring off Marius's hand as Valjean is resting, and then escapes when he sees Valjean getting up. When Valjean reaches the sewer's issue, he runs into Javert, who has been waiting for him. Valjean begs Javert to give him one more hour to bring Marius to a doctor, and Javert reluctantly agrees. After Valjean leaves, Javert, unable to bear the gift of Valjean's mercy to him, commits suicide by throwing himself in the River Seine.

Back on the streets, several women mourn the deaths of the young students Marius also mourns for his friends. As he wonders who saved him from the barricades, Cosette comforts him, and she tells him that she will never go away and they reaffirm their love. Valjean then confesses to Marius that he is an escaped convict and tells him that he must go away because his presence puts Cosette in danger. Valjean makes Marius promise never to tell Cosette, and Marius makes only a half-hearted attempt to hold him back.

Marius and Cosette are married. The Thénardiers crash the wedding reception in disguise as "The Baron and Baroness du Thénard" and tell Marius that Valjean is a murderer, saying that they saw him carrying a corpse in the sewers after the barricades fell. When Thénardier shows him the ring that he took from the corpse, Marius realises that he was the "corpse" and that Valjean saved his life. Marius punches Thénardier, the newlyweds leave, and the Thénardiers enjoy the party and celebrate their survival.

Meanwhile, Valjean prepares for his death, having nothing left for which to live. Just as the ghosts of Fantine and Éponine arrive to take him to heaven, Cosette and Marius rush in, in time to bid farewell to Valjean and for Marius to thank him for saving his life. Valjean gives Cosette his confession to read, and as he sleeps the souls of Fantine and Éponine guide him to Paradise, his long struggle over. The entire cast of characters, living and dead, asks once more, "Do You Hear the People Sing?