Foreign intelligence agent Mirsayid, captured by Soviet border guards, is sentenced by a court to a maximum security prison. He manages to conceal the location of the cache where the map is stored. Soon, new agents, Loinab and Guliam, successfully cross the border. Their goal is simple: to visit Mirsayid in the colony, find out the location of the cache, and retrieve the hidden map. The Chekists give them complete freedom of action for the time being.