Kristof returns from a night shift to find the Brodsky’s apartment door open. Sasha and Rachel inform him that two officers in gray uniforms arrested Felix, that morning—one of five Jewish men taken from their street. Rachel remains unnervingly calm, focusing on their finances and telling her children that Felix has been sent to a work camp and will return. She refuses Kristof’s suggestion that she and the children should try to leave Paris. Deeply distressed, Kristof feels powerless. He watches the street from his window, wishing he could protect the family.

The following Saturday, Sasha arrives at the library feeling defeated after an unsuccessful attempt with her mother to get information about her father from local authorities. She tells Gérard about her father’s arrest. Gérard sympathizes, revealing his own uncle was taken to a camp in Pithiviers. He tries to comfort Sasha by suggesting her father’s skills as a watchmaker might offer him some protection.

They discuss their coping mechanisms: Sasha’s memory project and Gérard’s violin practice. Gérard says he is currently working on Bach’s “Chaconne,” a difficult piece which helps focus his mind. Gérard walks part of the way home with Sasha. After they part ways, she hears the sound of a violin. She turns and sees Gérard at the corner, playing the “Chaconne” just for her. The unexpected gesture moves her to tears.

At Sainte-Anne’s hospital, Dr. Kristof finds that Dr. Claudel has been appointed as the official Military Liaison Officer. Kristof discovers that one of his long-term patients, Georges Plomin, has been sent to an unspecified “Eastern Facility.” Kristof is also shocked to recognize his old friend, Alesander Extebarria, among a group of Vichy officials in the ward. Dressed in a Vichy uniform, Alesander makes brief, ambiguous eye contact with Kristof before ignoring him. The encounter leaves Kristof questioning Alesander’s allegiance and whether he was always a spy.

The narrative shifts to Salpêtrière in 1664. Alouette is taken for her first medical treatment. The physician, Monsieur Moreau, uses her as a teaching subject for his apprentice, declaring that she suffers from an excess of bodily heat. He subjects her to bloodletting, draining a bowl of her blood. Sister Marthe pinches Alouette’s nose closed to force her mouth open so a purging liquid can be administered, making her vomit violently until she faints.

When Alouette wakes, another inmate named Marguerite gives her a soothing herbal drink. Sister Marthe soon arrives to take Alouette back to her cell, stating that the harsh treatments are for her own good. Alouette realizes with horror that her tormentors genuinely believe they are saving her soul.

Étienne pays a midwife named Mathilde Cadieux to smuggle a message and a small, carved stone lark to Alouette inside Salpêtrière. While he waits for a response, he practices his reading from a copy of Aesop’s Fables. The midwife returns hours later, explaining that a commotion prevented her from delivering the message herself, so she found a girl inside who promised to deliver it in exchange for a coin. She warns Étienne that some patients are considered “hopeless cases” and rumors that the infirmary deliberately lets women die.

At home, Étienne’s grandmother, Mémé, advises him to stop punishing himself with grief and to respect that Alouette made her own choices. That night, Étienne works on another stone lark carving and continues practicing his letters.

Alouette adapts to the grim, rigid routine of the hospital. One night, a guard named Jean-Baptiste corners her and claims to have a message for her from outside. He demands a kiss as payment for it. Alouette refuses, and he stalks off after threatening that she has drawn the “special interest” of Monsieur Moreau. Alouette confides in her cellmate, Sylvine, who confirms that guards often extort the women. Sylvine suggests that Jean-Baptiste might actually have a message and advises Alouette to bribe a different guard, Thibault, who needs money because his mother is ill. Sylvine gives Alouette a small pouch of coins she has saved. For the first time, Alouette feels a glimmer of hope.

Alouette finds Thibault and asks about the message, but he denies any knowledge of it before she can offer payment, claiming Jean-Baptiste must have lied. As he walks away, she catches a faint flicker of satisfaction on his face, leaving her uncertain of the truth. Feeling defeated, she devotes her energy to her work in the gardens. She is assigned an assistant, a frail girl named Christiane, raised as an orphan within Salpêtrière. Moved by Christiane’s circumstances, Alouette begins to teach her about the herbs. Christiane is an eager student, declaring herself Alouette’s apprentice.

During morning mass, Alouette is overcome with a wave of nausea and dizziness. She stumbles out of the chapel and vomits just outside the door. Her cellmate, Sylvine, quickly creates a diversion by loudly blaming the sickness on spoiled broth. Later, Sylvine privately confronts Alouette. Citing the recurring nausea, dizziness, and Alouette’s missed menstrual cycles, Sylvine asks if it is possible she is pregnant. Alouette is shocked, having attributed her symptoms to the stress and poor conditions of the hospital.

That night, Sylvine tells Alouette her story. She was sentenced for adultery and imprisoned. When her baby, a girl, was born in Salpêtrière, Sylvine was told it had been stillborn, but she was never allowed to see the child and believes she was lied to. She now lives for revenge. Sylvine says that guards routinely sexually abuse and extort the inmates and that she distributes pennyroyal, a herb used to induce miscarriages, among them. The conversation solidifies Alouette’s fears that she might be pregnant.

Kristof finds a note in his locked apartment from his friend Alesander Extebarria, asking to meet. Though Kristof fears a trap, he keeps the meeting. Alesander leads him into the Parisian souterrain, a network of underground tunnels. He explains that he is a member of the French Resistance working undercover. He details his recruitment into the Resistance, his work forging documents for Jews, the capture of his former cell, and his current assignment to infiltrate the Vichy administration.

Three days later, Kristof meets Alesander again, who leads him to a sophisticated resistance bunker deep in the souterrain. There, Kristof is stunned to find Ursula, the nurse who had disappeared from Sainte-Anne’s hospital. Alesander and Ursula show Kristof captured German documents detailing Aktion T4, a program for the systematic euthanasia of psychiatric patients. They explain that the program, which involves deliberate starvation, is being implemented in Paris. Ursula reveals that her uncle, a Viennese psychiatrist, was murdered by the Nazis for resisting similar orders. Alesander asks Kristof to join their network and help save patients. Afterward, walking together through Parc Montsouris, Kristof is shocked to hear Alesander’s eye-witness account of the murder of children at a T4 facility in Germany.

Kristof recruits Julian, and a trusted senior doctor, Eric Anouilh, to help the resistance. Working secretly, they alter the medical files of patients targeted for transfer, changing their diagnoses to make them appear “salvageable” and thus ineligible for euthanasia. Ursula warns them the next transport convoy leaves soon with 22 names on the list, forcing them to choose which patients to prioritize.

As he leaves the hospital one night, Kristof spots Julian across the courtyard. At the same time, he sees two men who look like Gestapo agents watching them. Julian gives Kristof a pre-arranged hand signal, warning him to stay away. Feigning casualness, Kristof waves back and walks out of the gate, terrified that a trap is closing around his friend.

In the early morning hours of July 14, 1942, French police begin a mass roundup of Jews. An officer pounds on the Brodskys’ door and gives the family five minutes to pack. In a panic, Sasha gathers a few items, including her copy of Metamorphoses and medallion from her father. Kristof hears the commotion and appears in the hallway. Kristof is briefly allowed to enter to comfort a crying Klara. The police take the family from the building. As they are led down the stairs, Sasha looks back and sees Kristof standing helplessly in the hall.