Alexey Kupriyanov, nicknamed Cooper, lives in the Arsenal, one of the industrial districts of the Russian hinterland. His life changes after the murder of his friend in order to conduct his own investigation, and Captain Kupriyanov leaves the operations department and becomes a district inspector. Everything in his Arsenal is his own, his own: his ex-wife with her problems, his son in transition, the beautiful girls, the locals who turn to him for help, and even the bandits who terrorize the town. But Cooper is not a timid person, and he knows exactly how to deal with all this...