His son Stepan was found murdered in the house of pensioner Efimov. The matter is complicated by the fact that all suspicions fall on Beagle Agency employee Dusan Petrovich. Petrovich violated the orders of his boss and went to the pensioner’s house to help Stepan find an ancient treasure hidden in the house. Prosecutor's office investigator Borodulin promises Rostovtsev to put Petrovich behind bars. The whole team does not believe that Petrovich is guilty and is trying to help their friend. Together with Yunga and Alina, Andrei Rostovtsev manages to solve this crime, which has roots in the distant past.