With filming underway at the police station, the actor Tom Duval's assistant is found dead in a crime committed under the very noses of the police, on their premises. A real challenge for Cherif and Briard, who also face an internal investigation.

While heading for the police station, Déborah barely escapes a mysterious gunmen on a motorbike. A passer-by, Paul Blanchard, is not so lucky and dies. During the investigation, Chérif and Briard discover that Blanchard was involved in kidnapping the daughter of a major industrialist from Lyon.