Nina Dorval’s investigation into the murder of two infants is an effort to reconstruct a crime concealed inside the routines of childcare. Faced with Louise’s coma and a chorus of testimony describing an exemplary nanny, Dorval follows discrepancies in the day’s movements, studies surveillance footage, searches Louise’s history, and ultimately plans to reenact the afternoon in the Massé apartment. The inquiry does not yield a simple explanation; its force lies in the gap between a life that others say they barely knew and the minute, ordinary gestures through which Dorval tries to recover what happened.

The Investigation and Its First Leads

Dorval works backward through the events, determined to find a break in the account despite Louise’s silence and the consistent descriptions of her as an irreproachable caregiver. At the police headquarters known as 36, she questions Wafa, who is crying and initially unable to speak. Dorval brusquely sets aside Wafa’s immigration status, employment contract, and trust in Louise; what matters to her is whether Wafa saw Louise that day.

Wafa recounts arriving at the apartment in the morning. Louise opened the door only partway, and Wafa thought she seemed to be hiding something. Alphonse slipped past her into the home and found the children in their pajamas, watching television. Wafa tried to persuade Louise to let them go for a walk because the weather was fine and the children would be bored, but Louise refused to let her in. Wafa called Alphonse, who was disappointed, and left with him. Her account establishes both Louise’s refusal of help and the children’s presence in the apartment, but it does not explain what Louise did afterward.

A second account sharpens the uncertainty. Rose Grinberg is certain that she encountered Louise in the building’s hall about an hour before the children’s nap—and an hour before the murder. That sighting contradicts any assumption that Louise remained at home throughout the interval. Dorval and the other officers search the surrounding neighborhood with Louise’s photograph, questioning people at the square, the café Le Paradis, the passages off Rue du Faubourg-Saint-Denis, and local shops. The search moves through public places and unreliable recollections, without immediately clarifying where Louise had been or how long she was away.

Surveillance and the Ordinary Afternoon

The supermarket recording gives Dorval a visual record to examine repeatedly. Louise enters the aisles with the children and calmly selects a carton of milk, a packet of biscuits, and a bottle of wine. The children move around her: Adam knocks over packages and bumps into a woman pushing a cart, while Mila reaches for chocolate eggs. Louise does not call to them or visibly follow them with her eyes. They eventually run back to her laughing, and Adam tugs at her skirt, but she ignores them. Dorval notices only a slight tightening of Louise’s lip and a furtive downward glance, reading these small signs against the image of a composed caregiver.

The footage matters not because it directly records the killing, but because it complicates the familiar picture of Louise’s attentiveness. Dorval interprets the children’s unmonitored movement through a fairy-tale image: Louise resembles a mother who abandons children to the darkness of a forest. This is the investigator’s reading of the footage, not a confession or proof of motive. The recording makes ordinary shopping look newly ominous while leaving the crucial events outside its frame.

Dorval lays the recording beside the day’s other timings. At four o’clock, Rose Grinberg closed her shutters; Wafa had walked to the square and sat on a bench; Hervé had finished his shift. At that hour, Louise went toward the bathroom. The investigation thus narrows toward an apparently domestic sequence: children, bath, and a caregiver whose routines had been trusted. Dorval asks Paul whether Adam and Mila liked water, whether they usually resisted undressing, and whether they enjoyed splashing among their toys. She considers whether the unusual timing of a bath at four in the afternoon might have provoked a quarrel, suspicion, or surprise.

The Weapon and the Material Clue

When Dorval shows Paul a photograph of the murder weapon, he identifies it without needing time to think. It is a small, extremely sharp ceramic knife that Thomas had brought the family from Japan. Its ordinary appearance and compact size make it possible that Louise could partly conceal it in her palm; even touching it could cut the skin of a fingertip.

The knife also carries a trace of the household’s attempts to keep danger at a distance. Myriam had given Thomas a one-euro coin in exchange for it, a gesture intended to ward off bad luck. The family did not use the knife for cooking: Myriam stored it high in a cupboard, beyond the children’s reach. The object therefore connects a domestic gift, a protective superstition, and a precaution taken for the children with the weapon Dorval is investigating. Paul’s identification establishes where it came from and how it was kept, but the passage leaves the question of premeditation open.

Searching Louise’s Past

After two months of investigation, day and night, Dorval feels she knows Louise better than anyone. She summons Bertrand Alizard, who trembles and sweats in the 36’s office. Alizard is so afraid of blood and unpleasant surprises that he stays in the corridor while police search Louise’s studio. The search yields little: empty drawers, spotless windows, a photograph of Stéphanie, and several unopened envelopes. The spare room offers no ready explanation, only a few remnants of a private life.

Dorval broadens the inquiry through people and records connected to Louise. She questions the Rouviers, M. Franck, Mme Perrin, and doctors at Henri-Mondor Hospital, where Louise had been admitted for mood disorders. She spends hours reading Louise’s flower-covered notebook, with its carefully written, unfamiliar names, and searches out neighbors from the time Louise lived in Bobigny as well as nannies from the square. Their recollections repeatedly reduce to a greeting exchanged in passing; no one claims to have known her closely. The abundance of interviews and documents therefore does not produce a coherent portrait. Louise remains socially difficult to place even as Dorval gathers details about her.

The investigation’s central obstacle is not merely a lack of evidence but a lack of intimacy: almost everyone has seen Louise, yet few can say they knew her. Dorval’s pursuit of the past reaches from hospital records and a notebook to unopened letters and scattered acquaintances, but the material remains resistant to interpretation. The novel presents the detective’s growing conviction that she understands Louise alongside the failure of those around Louise to describe her as more than a familiar, distant presence.

Reenactment as a Search for Meaning

Dorval believes that a reconstruction can sometimes act as a revelation: once a scene is physically repeated, a detail may emerge or a contradiction may become intelligible. She plans to return to the Rue d’Hauteville building, where bouquets and children’s drawings still mark the entrance, step around the candles, take the lift, and enter the apartment. Nothing there has changed since the day in May, and nobody has come to collect belongings or even retrieve papers. For Dorval, this preserved domestic setting becomes a stage on which the sequence may be played again.

The planned reenactment follows a chain of bodily actions rather than an explanation supplied by Louise. Dorval expects to turn on the tap and test the water with her hand, as she once did when her own sons were small. She will summon the children to bathe. She imagines the apartment’s disorder—the washing machine, the dirty sink, toys spilling from their boxes—and the exhausting paths between bedroom, kitchen, bathroom, rubbish bin, dryer, bed, entrance cupboard, and balcony. In trying to inhabit Louise’s movements, she will reach for the knife in the cupboard and drink a glass of wine by the open window, one foot on the small balcony.

The sequence is a planned procedure, not a confession or a completed explanation of the killings. Its power comes from the collision between routine care and violence: testing bathwater and calling children are ordinary acts, but the investigation places them beside the concealed knife and the deaths. Elsewhere, Louise’s caregiving already blurs into control: in hide-and-seek she stays hidden while the children panic, and after Mila has gone missing she warns the girl that nobody would come if she were taken away. Dorval’s return to the bathroom therefore retraces not only the final afternoon’s movements but the book’s repeated tension between care as protection and care as a form that can turn frightening. Her reconstruction offers a way to search for a missing sequence; it does not erase the silence that made the search necessary.