La Motte begins the morning by scolding Peter, who was meant to keep watch and slept through the night, and who answers that sleep is the only comfort to be had in such a place. Then La Motte creeps down the tower stairs, peeps through a half-open door and sees a stranger sitting by the window. He scrambles back to the closet, but footsteps follow him and a voice calls him by name, so he flees to the vaults and throws himself down at the far end. Madame La Motte's shriek makes it worse. He tells her she has destroyed him, cries that Dupras is avenged, and heads for the door to give himself up. His wife begs him to stay, and Adeline points out that officers who had found the trap-door would have reached them by now. The silence holds for a whole day and night, until hunger forces a plan: Peter will go to Auboine for food and wheel parts, forbidden to ask anything about the people who came looking for La Motte.
Someone must first check whether the abbey is empty. La Motte cannot go, since he has already been seen. Peter has courage but no wit, Annette has neither, and Madame La Motte shrinks from the task. Adeline offers herself, saying that La Motte once saved her from great danger and she wants to repay him. Ashamed, he accepts and calls himself her debtor. The moment she leaves, Madame La Motte's admiration curdles into doubt: only love, she decides, could make a girl so brave. Adeline creeps through the empty rooms, past her tame fawn, and is almost back at the tower when a man in a soldier's dress steps out of the hall passage. She runs and he follows, gently saying that he knows La Motte is hiding in the ruin and must see him. She refuses to help, but he searches the chambers himself, and she talks loudly so that La Motte will hear. When the trap-door lifts and La Motte appears, the two men embrace. The stranger is his son Louis, and Adeline guesses it before La Motte can say the word.
Louis explains how he found them. A letter from Monsieur Nemours reached him at Peronne, he spent weeks in Flanders with his regiment, and then he took leave and followed his father's trail south. At one inn he recognised a line of verse scratched on the window glass, and at Auboine his landlord described what had happened at a blacksmith's shop, and described Peter so exactly that Louis felt certain. The joy is short. La Motte fears that his son's questions have made the villagers curious, and he is shaken to learn that a hard search for him is still running in Paris. Louis argues that the abbey is safe, because the country people think it is guarded by a supernatural power. He repeats their story: years ago a man was brought privately to the abbey, was never seen to leave, and "came unfairly to his end", and his ghost walks the ruins. La Motte sighs, and when Louis says nobody used the word murdered, La Motte repeats the phrase and Adeline calls it "a nice distinction". La Motte then turns the rumour into cover. He sends Louis back to the inn at Auboine to say the abbey stands empty and to hint at a dreadful apparition, and the plan works.
The peace does not last. La Motte's joy fades, and he goes back to his haunt in the forest. Madame La Motte, who cannot admit her jealousy to anyone, asks Louis to find out what troubles his father. When she describes Adeline coldly, her coolness backfires and makes him pity the girl more. Louis follows his father into the woods, loses him, and reaches a gloomy recess with the ruins of a tomb. A figure rises under the arch and vanishes. Louis calls and gets no answer, goes a few steps down a dark passage, remembers robbers and retreats. Back at the abbey he finds La Motte sitting in the parlour as if he had been there for half an hour. Madame's unkindness to Adeline is now plain, and when Adeline begs for an explanation, Madame evades her and drops hints that leave her more confused.
One sleepless dawn, Adeline walks to a glade by the river and sings a sonnet to the lily. An echo answers, then a voice, and she sees a young man in a hunter's dress watching her. She hurries home and decides not to tell La Motte, who has fears enough. At breakfast Madame La Motte needles her about her "pleasant companion". Adeline answers that those who have lost their last friend have little to be happy about, and Madame, rebuked and blushing, replies that a friend is only estimable when our conduct deserves one. Adeline leaves in tears, Louis defends her and is accused of being caught in her trap, and La Motte storms out, telling them to keep their petty quarrels private. The narrator explains the cause. Madame had heard of Adeline's walk, knew that La Motte had gone out early, and assumed a meeting, so that every small thing became proof.
Louis then joins his father on a walk and describes the tomb. La Motte warns him off, saying that robbers may be near and that their only safety lies in staying undiscovered. When Louis asks the cause of his sadness, La Motte, pale and trembling, says he has no distress beyond what Louis already knows and forbids the subject. Adeline spends the day alone with her sewing and her books and, at evening, recites verses to the night. Louis finds her walking, tells her he is sorry for the scene at breakfast and offers to speak to his mother, which she refuses. His tender tone tells her, for the first time, what he feels. She quickens her pace, and neither speaks until they reach the abbey, with the figure in the tomb, the stranger by the river and the cause of La Motte's grief all still unexplained.
