MUR operative Konstantin Troshin returns from the front after winning the Great Patriotic War and learns that he no longer works in the police. The reason is a conflict with an influential general of the NKGB USSR. But without the police, Troshin cannot imagine his life. He manages to get a precinct in the most disadvantaged area of Moscow - Maryina Roshcha. Due to personal problems, Troshin is forced to settle in a communal flat, here, in Maryina Roshcha. Being in the epicenter of the criminal environment and closely converging with its inhabitants, Troshin unravels cold-blooded murders, daring raids and cunning scams. But not the criminals goal Troshin. He sets himself the task of eradicating the crime itself. Being in the position of a district police officer, he gradually becomes an arbitrator, whom people trust to separate good from evil.