Julien Auclert [Vincent Lindon] and Lisa Auclert [Diane Kruger] are a young, ordinary couple raising their infant son Oscar, until a shock shatters their world: police storm their apartment and arrest Lisa for murder, and a cour d’assises later sentences her to 20 years in prison.
Three years pass, and Julien keeps searching for evidence that might prove Lisa’s innocence. Yet the case stubbornly points to her as the prime suspect. The victim was Lisa’s boss, with whom she had a heated argument on the day of the crime. The murder happened in a parking lot outside the office, with the boss killed by a blow to the forehead using a fire extinguisher, and Lisa’s fingerprints found on the extinguisher. A flashback reveals an unknown woman killed the boss, grabbed her purse, and bumped into Lisa; during their exchange, the boss’ blood smears on Lisa’s coat. Lisa explains she picked up the extinguisher instinctively after seeing it on the road, unaware that her boss lay dead beside her.
Desperate, Julien seeks help from Henri Pasquet [Olivier Marchal], a former criminal who has escaped from prison seven times and written about escape methods. Pasquet explains that no prison is airtight and every system has a “key” to freedom. He warns that the hardest part is staying free, since many escapees rush back to their families or friends. His plan is stark: sever all family ties, flee the country through a foreign airport, adopt new identities with fake documents, move to a country with no ties to French communications, and have enough cash to sustain the family for years. With this, Julien begins a meticulous process, drawing a sprawling mind map on the wall at home—an ever-growing map of the prison’s layout, routines, and possible gaps to exploit.
For three months, Julien visits the prison, studying security routines and any irregular activity that could reveal the coveted “key.” The mind map on the wall becomes a detailed tapestry of connections, photos, and notes, fueling his resolve.
Meanwhile, new pressures mount. Dr. Gardes reveals that Lisa, who is diabetic, has refused to take her insulin for several days; he fears she might be attempting suicide to spare Oscar the strain of visitation. Lisa explains she does not want their son to suffer or be unhappy, adding to Julien’s urgency. In a bid to fund their escape, Julien ventures into a dangerous world in a quest for fake documents. He is mugged by two men posing as dealers, but a biker intervenes with a more promising offer: complete fake papers in a week for €2,500. The deal goes smoothly, and Julien also steals Lisa’s medical records from a delivery van to strengthen his façade. He sells their furniture to raise additional funds, tightening the screws of their plan.
News arrives that Lisa will be transferred to Rennes in a few days. Julien, now pressed to secure every euro, attempts a bank robbery but withdraws at the last moment. Undeterred, he confronts a drug dealer and, after a tense confrontation, aligns with a larger dealer named Martial Nashour [Moussa Maaskri], recovering a substantial amount of money through a gunfight. The following day, Julien tears the mind map from the wall and discards its contents in a dumpster, then abducts Oscar and leaves the apartment. He sneaks into the medical delivery van, inserting an altered version of Lisa’s records. He abandons his car, rents a new vehicle, and hides with Oscar in a hotel nearby.
Dr. Gardes reads the forged records, prompting Lisa to be transferred to the nearest hospital. At the same time, police investigate Martial’s death and discover a taillight fragment from Julien’s car, tying him to the crime. They converge on the hospital, where Julien and the guards are confronted, but Julien disarms the guards and retrieves Lisa. The two flee to Liège Airport in Belgium with Oscar and reunite, briefly, before the truth catches up again.
Back at the police precinct, the recovered mind map is pieced together, but investigators determine it’s too late—the Auclers have already vanished, slipping beyond reach to San Salvador. The map’s fragments hint at a carefully laid plan that succeeded in outpacing the authorities, at least for now, as Julien and Lisa begin a new, clandestine chapter away from France.
