The movie is set during the last days of a foreign intervention against Soviet Russia. Police are searching everywhere for a Bolshevik named Brodsky but cannot find him. Meanwhile, a man named Michel Voronov serves as a teacher to a rich woman's son, Zhen'ka.
At the end of the 19th century, a series of mysterious murders occur in the provincial city of N. Metropolitan investigator Goremykin arrives at the crime scene. The search for the perpetrators leads to an unexpected conclusion – a revolutionary circle within the city, which consists of two young men recently returned from Switzerland.
Like many boys and girls whose early years included the Great Patriotic War, 16-year-old Dusya was eager to go to the front. She and her family lived not far from Sukhumi, and not a week passed without Dusya stopping by the local military registration and enlistment office. Each time the military commissar refused to grant her request, but Dusya did not give up and one day she was offered to enter an intelligence school.
