The fate of detectives encounters a variety of people. And they often intersect with homeless people - they are witnesses, victims, and suspects. But for a homeless person to replace a detective... This happened when Russian police captain Zaitsev was investigating a murder case. Near the crime scene there was a citizen of no fixed abode named Ivan, who, as it turned out, had a keen eye, observation and analytical mind. It was with his help that Zaitsev identified the killer, solving a seemingly completely cold case. And then - more. A new crime - and the captain again goes to the quick-witted tramp...