At the airport, during the arrival of the new star recruit for OM, by sheer chance, Thomas Chevalier, a Parisian cop with an exemplary career, is forced to intervene to neutralize an assailant attacking the footballer. However, the player is injured, leading to a fiasco and Chevalier's punishment: a transfer to Marseille. There, Captain Chevalier leads an unorthodox team determined to make his life difficult. Together, they investigate the murder of Sofia Rimini, a thirty-year-old shot and found with a lottery ticket in her mouth.

While on leave with his two children visiting him in Marseille, the discovery of a diver's corpse washed ashore prompts Chevalier to return to duty. Mysterious maps, secret passages, treasures—this investigation takes the entire team on an extraordinary adventure.

A madman storms into the police station, taking Thomas Chevalier hostage in the evidence room. Nora and her team will do everything in their own way to save their leader, even if it means defying the determined RAID forces set on strictly following the procedure.

An abandoned infant is found on a drifting Zodiac in the calanques. Blood traces on the boat lead the team to conclude it's not a survivor but a murder victim. During the investigation to locate the child's family, the cops confront lawless individuals.