The operatives of the Department of Internal Affairs in the Commandant's district of St. Petersburg, Leonid Lavrov and Yuri Romanov, are complete opposites of each other. Romanov is an exemplary family man, an athlete. Lavrov is a ladies' man, a regular in the most seedy places of the city. Each of their meetings ends with a heated argument.

The authorities have long learned to benefit from the eternal disagreements between the two operas — after all, each of them not only has its own views on life, but also its own approaches to operational investigative activities. Romanov always tries to act within the law. Lavrov, on the contrary, believes that it is important to get results quickly, and it does not matter whether by legal or illegal methods.

But despite all the disagreements, in case of serious danger, everyone is ready to turn their backs on each other. Although, it is difficult to imagine a situation that could upset Lavrov and Romanov - both operatives have long treated any risk with equanimity. It is for such icy calmness that colleagues call them "Tough Nuts" behind their backs.