Last Known Address

Marceau Léonetti, an energetic officer, stops by chance the son of an influential lawyer who is driving under the influence. The incident puts him under scrutiny from the lawyer and foreshadows the later conflict. It establishes Léonetti's competence and sets up the lawyer's motivation for a later false accusation.

A few months later, the lawyer falsely accuses Léonetti of violence and incompetence. The accusation leads to Léonetti's transfer to a small police station. There he has little to do beyond recovering stolen pigeons, illustrating the dull routine of his new posting.

An old colleague, now head of a special crime unit, recruits Léonetti. He meets young officer Jeanne, and they are tasked with catching men who sexually harass women in cinemas. Jeanne acts as bait in a sting operation.

Léonetti and Jeanne are assigned to locate and arrest Roger Martin, the only witness who can testify at the murder trial of master criminal Soramon. With the prosecution's other witness dead, Martin's testimony is crucial. The police only have his old address in the Cité de la Glaciére.

They search for Martin by tracing his old furniture he sold when he moved. The hunt takes them through the city as they chase down scraps of his past. The absence of a current address complicates the pursuit.

During the investigation, they learn Martin may have a young daughter. A clue points to her taking medication in the form of blue pills. Martin's former neighbour confirms the daughter's existence.

Soramon's criminal associates begin tailing Léonetti and Jeanne, hoping to uncover Martin's whereabouts. The danger increases as leads dry up and the stalkers close in. The pair stay focused on finding the daughter and the address.

Léonetti proposes checking pharmacy records to find the daughter's prescription. After a long search, on the first day of Soramon's trial, they locate a record that leads them to Martin's doctor. The breakthrough re-energizes their pursuit.

Leaving the pharmacy with the address, Léonetti and Jeanne split up. On the street, a gang attacks Léonetti; he fights them off but is badly beaten. The gang steals what they think is the note with the doctor's address, but Léonetti has already given the address to Jeanne.

At the doctor’s surgery, they learn Martin and his daughter have an appointment that day, not just an old address. Léonetti apprehends Martin as he leaves the surgery. Martin and his daughter are taken to a hotel under police protection.

Martin testifies at court the next day. After the testimony, the police leave him unguarded, which allows the Soramon gang to strike. He is assassinated in the park, in view of his young daughter.

Jeanne expresses disillusionment with police work, saying the payoff of Soramon's conviction was not worth Martin's death. Léonetti bluntly responds, and Jeanne says goodbye before driving away. The film ends with a philosophical misquote about life and living it fully.