The film is based on real events that took place in Moscow in the early 1980s. A KGB officer in plain clothes returning late at night is detained by a police patrol at the Zhdanovskaya metro station. The officer, who began to actively protest against the arbitrariness, was taken to the police duty room and severely injured. After that, the police officers decided to finish off their victim and take the body away and dump it outside the city. The investigation is entrusted to Gleb Yarin, an investigator with the USSR Prosecutor's Office. Soon he finds himself involved in a confrontation between two irreconcilable rivals — the KGB and the Ministry of Internal Affairs. The senior police leadership is determined to cover up the scandal between the security agencies by any means necessary.