La Chèvre

Marie Bens, daughter of a CEO, is abducted while on vacation in Puerto Vallarta. The police struggle to find leads, and the case grows cold. Her father hires Campana, a private detective specialized in disappearances, to take over the search.

Campana stays in Mexico for a month, pursuing any possible lead but comes up empty at every turn. His frustration grows as the disappearance defies typical investigation methods. The case seems unsalvageable for conventional detectives.

Mr. Bens turns to Meyer, the company psychologist, who argues that Campana's 'normal' detective instincts won't crack the case. He proposes Perrin, an accountant whose life is a string of mishaps, as the perfect counterbalance to bad luck. Meyer demonstrates Perrin's luck by having him choose a chair; he picks the broken one and falls.

Despite initial reluctance, Campana agrees to team up with Perrin and starts guiding him as the 'goat' of bad luck. Perrin approaches the case with seriousness, treating it as a real investigation rather than a ridiculous joke. They depart to begin the search.

Their journey begins at Orly Airport and continues through Mexico, with Perrin's misfortunes complicating every step. Campana is baffled and exasperated by the oddball partner, but the duo persists in chasing leads. The escalating mishaps, ironically, push them toward a real suspect.

The French duo traces the kidnapper to a man named Juan Arbal. They close in on him, but Arbal is killed by his own gang to prevent him from talking. The trail seems to vanish just as they confront a critical witness.

Following Arbal's death, Campana and Perrin are arrested by local police who mistake them for the murderers. Campana is beaten, and he fears that Perrin's luck might have rubbed off on him. The pair's status hinders the investigation rather than helping it.

They assist in arresting Fernando, the gang leader, who admits he doesn't know what happened to Marie. He explains the small plane transporting her to a hideout vanished in the rainsforest, accounting for the lack of ransom notes. The mystery deepens as the key evidence seems to be in the air.

Meyer convinces everyone to take one final gamble by placing Perrin on a plane to search the jungle from above. A diversionary plan goes awry as the plane must make an emergency landing in the wilderness. This setback keeps the unlikely duo on the ground and in peril.

Campana and Perrin abandon the aerial search and traverse the forest by Jeep, only to become hopelessly lost with dwindling fuel. The dynamic between them explodes as Perrin's luck seems to dominate, and Campana reveals he is merely a 'goat' for bad luck. Perrin suffers a clash that knocks him unconscious.

Locals rescue the duo and take Perrin to a mission for care. Campana phones Meyer to halt the search, deciding to end the operation. In the infirmary, Perrin wakes to find Marie Bens recovering in a neighboring bed.

Marie and Perrin, walking hand in hand toward a pontoon bridge, drift away when the dock collapses. Campana looks on, astonished, as the two unlucky companions disappear into the river's current. The ending leaves their fate uncertain but united.