The action takes place in the Northern capital during Soviet times. The protagonist is a Siberian man named Alexey Severtsev, who travels to Leningrad. The naive and simple-minded man is deceived by cunning criminals. They lure the trusting Severtsev to a secluded place, beat him up, and steal all his belongings. A young police officer named Nikolai Zakharov takes on the investigation of this case. He displays resourcefulness, wit, and courage in order to arrest the repeat offenders.