As he mournfully enters his room, he is followed by Jondrette's older daughter. Marius is piqued at her since by giving her his last five francs he has lost the opportunity to follow his elusive sweetheart. His resentment is particularly unfair, for the young girl's visit is motivated only by compassion and gratitude. She has noticed Marius' depressed air and is offering her help. Marius asks her to discover M. Leblanc's address. The young girl agrees, although with a sadness that Marius does not notice.
Alone again, Marius plunges into a poignant reverie. He is disturbed by Jondrette's excited comments about M. Leblanc and his daughter. Hoping to obtain some vital information, he jumps back on his observation post. He learns that Jondrette has recognized in M. Leblanc an old acquaintance, although obviously not a friend since his wife greets the news with venomous rage. Jondrette, however, is pleased by the discovery since he thinks he will be able to extort vast amounts of money from this old man. He has evidently hatched a sinister plot, judging from the ominous instructions to make up a fire which he gives his wife. Then he leaves to further perfect his trap.
Marius quickly resolves to checkmate whatever mischief Jondrette is planning. After a brief hesitation, he quietly sets out for the police station. On the way, he overhears a conversation between two disreputable characters that confirms his suspicion that a net is closing around M. Leblanc. At the police station, he is met by an inspector of impressive height with a piercing gaze. The interrogation is incisive and to the point. After his briefing, the policeman requests Marius' passkey and tells him to return home immediately. He is to observe the execution of the plot and, when the trap is about to be sprung, to shoot in the air as a signal to the police. As Marius leaves, as an afterthought the inspector gives him his name: Javert.
A little later, Courfeyrac and Bossuet, Marius' student friends, run into him on the street, but he is unaware of their presence as he is intently following Jondrette. The latter, not suspecting he is being followed, enters a hardware store and comes out with a chisel. Then he disappears into the shop of a man who hires out carriages. Marius gives up his spying to return home before the house is locked up for the night. On his way to his room, he glimpses four men lurking in one of the empty apartments, but fearing to be seen, he refrains from investigating.
In his room, he hears Jondrette returning, then giving various instructions and sending the two girls into the street as lookouts. He climbs back on the dresser and peers through the hole. The room is illuminated by an eerie red glow produced by a sizable stove full of burning coal, with a chisel in the middle of the fire. In a corner he notices two piles, one of old pieces of iron, the other of rope, which upon close examination turns out to be a ladder. Jondrette places two chairs at a table, lights his pipe, and waits.
The church bells strike six and, as agreed, M. Leblanc comes in. His first act is to hand Jondrette more money for his rent and his immediate needs. While he thanks him profusely, Jondrette manages to give his wife a disquieting order—"Send away the cab." Jondrette and Leblanc sit down and Jondrette holds his attention with talk while, unobtrusively, a man enters the room behind the old man's back. Warned by a kind of instinct, M. Leblanc turns and perceives the new arrival. Jondrette explains him away as a neighbor, and the same explanation covers the arrival of three more sinister figures.
Then he explodes his bombshell: "Do you have your wallet? I'll settle for a thousand crowns." Leblanc, alarmed by this blackmail, stands up with his back to the wall and stares at him suspiciously. Like a cat playing with a mouse, Jondrette turns to more innocent conversation. Suddenly three armed men walk in and Jondrette ceases his pretense. In a thunderous voice he says to Leblanc: "Do you recognize me?" Leblanc, pale but far from intimidated, retreats behind the table and steels himself for action, declaring he does not know Jondrette. Jondrette cries, "I am not Fabantou. I am not Jondrette. I am Thénardier."
The revelation leaves Leblanc unmoved, but not Marius. He is stunned, for he finds himself confronted by an impossible dilemma: save Thénardier and sacrifice an innocent man, or call the police and betray his father's trust. He has no time to deliberate, for events move rapidly. Thénardier savors his triumph with hysterical glee, pouring out a flood of reproaches, threats, and boasts; Leblanc calmly replies that Thénardier is mistaken—he is not a rich man, and they have never met before. But, as Thénardier turns around to speak to one of his accomplices, the prisoner springs to the window and nearly escapes. It takes three men to bring him back, and after a titanic struggle, he is tied to one of the beds.
Thénardier then sends the gang out and tries another tactic. Shrewdly he points out to Leblanc that in spite of his danger he has never called for help. Can it be that he is afraid of the police? With elaborate casualness, he moves to give the old man a view of the red-hot chisel and proposes a bargain—200,000 francs for Leblanc's freedom. With the smile of a "grand inquisitor," he invites Leblanc to write a letter to his daughter asking her to come to him; she will serve as a hostage to insure that Leblanc pays the money. Silently, Leblanc writes, signs his name, and gives his address. Convulsively, Thénardier grasps the letter and sends his wife out with it to get the girl. They wait in a long and dreadful silence until Mme. Thénardier returns in a fury. They have been duped: Leblanc has given them a false address.
While she has been gone, however, Leblauc has used a miniature saw hidden in a hollow coin in his pocket to cut his bonds, and he is free except for one leg. He leaps to his feet and defies them, seizing the red-hot chisel in one hand. "You will never make me write what I do not want to write," he cries, and disdainfully puts the chisel to his own arm, watching it burn without a quiver; then he flings the chisel out of the window. The gang falls upon him, and Thénardier, deciding there is nothing left to do but kill him, takes a knife from the drawer.
Marius is in an agony of indecision, but he can no longer delay—it is Leblanc or Thénardier. Suddenly he has an inspiration: During her visit that morning, Thénardier's daughter had written on a piece of paper to show her education, "The cops are here." Marius grabs it and throws it through the crack in the wall. The gang reacts just as he has hoped. They rush to the window in a disorderly panic.
But their escape is foiled by Javert's dramatic appearance. His authority reduces them to a flock of sheep. Thénardier alone among the men offers some resistance; he aims a pistol at Javert, but the gun misfires. In bestial fury, his wife hurls a rock at the inspector, who simply ducks. The police put handcuffs on the gang, and the three masked men are identified: they are Gueulemer, Babet, and Claquesous, three of the four bandit chiefs of Paris. His prisoners secured, Javert looks around for the victim, but in the confusion he has vanished. "The devil!" says Javert. "He must have been the best catch of the lot."
The next day, Gavroche goes to see his parents, impertinent and carefree as usual. He finds the door to their apartment closed, and an old lady whom he has just insulted informs him that his whole family is in jail. He greets the news with a casual "Ah!" and with a song on his lips returns to the wintry street.
