When an important cache of seized heroin is stolen from a regional customs depot and two officers left dead, it becomes clear that there is a mole within the customs service. Commandant Sandra Longo, of internal affairs is dispatched from Paris to unmask the traitor. Her investigation leads to Cominetti, a businessman whose maritime transport firm is a front for a major drug ring. Longo sets her sights on trapping her man, with the help of Laure, an undercover customs agent, and the police captain investigating the murder of the two customs agents.