Marc and his friend Franky begin a career in the Gendarmerie. The corps is in a deep crisis after the drug criminality of one of the officers is uncovered by Major Vernaillen. Marc is allowed to start as a secretary with the major and thus ends up in the middle of the internal struggle within the gendarmerie. Franky, in turn, is noticed by Madani Bouhouche, a gendarme who does not take the legal requirements too closely. Student Vicky distances herself from her brother Franky and Marc because, as gendarmes, they are unpopular on the leftist university campus.

After the attack on Vernaillen, Marc is protected by his new superior, adjutant Goffinard. Franky then jumps to the defense of his boss, adjutant Debels, who went way over the line in a racist incident. As thanks, Debels introduces Franky to Group G, a shadowy organization of far-right gendarmes. Madani Bouhouche seeks revenge after his dismissal from the gendarmerie.

Marc discovers with Goffinard that there is a connection between several, at first glance unlinked serious crimes. But Goffinard forbids Marc from sharing that info with other services. He doesn't want any prying eyes. Franky gradually becomes entangled in the far-right network. Vicky misses her brother, but fails to catch Franky yet. Marc, on the other hand, secretly goes to the parties where Vicky DJs. Major Vernaillen becomes more and more isolated.

At a demonstration, Marc as a gendarme and Vicky as an activist face each other. When a group of students attacks Marc, Vicky saves him. It brings them closer together. As a reward for his discretion, Franky is allowed an internship with the Diane Brigade. Marc and Goffinard discover that several of the recent murders can be linked. Vernaillen secretly conducts a parallel investigation.

Marc and Vicky build on their secret relationship, but discussions about drugs and their political antagonisms create tensions. Franky gets to work as a security guard at a minister's private party. During a robbery at a department store in Nivelles, three people are cold-bloodedly executed, including a gendarme. The robbers wait for the police to shoot them: the Brabant killers are born.

Vicky has graduated as a lawyer and now lives with Marc. The latter is conducting a secret investigation into the Gang with Goffinard. Vernaillen is promoted away. The Group G thinks Marc is getting too curious about their activities and send Franky after him. It evolves into a painful confrontation between the two friends.

After several deadly raids, the Gang suddenly seems to have stopped its attacks. The investigation has ground to a halt and Marc has been transferred to a department where he has to do administrative work, much to his frustration. Franky increasingly flees into hard drugs. Bouhouche is worried because Juan Mendez suspects him of stealing his weapons collection. Vernaillen continues to work on his private investigation and shares his findings with Marc. Vicky refuses to violate her professional secrecy as a lawyer to help Marc.

Bouhouche is arrested for the murder of his friend Mendez. Together with Goffinard, Marc eavesdrops on prison conversations between Bouhouche and his wife. This is how they find out where the gang's weapons are located. During the observation of that locqtion, it gets to a showdown.