1965. A seventeen-year-old boy is killed on the outskirts of Moscow. The suspicion falls on his friend but Major Tcherkasov, the best detective of the USSR, doesn't believe it. The evidence leads him to one of the most ruthless killers in the years of the Great Patriotic War. The plot is based on the true story of executioner Antonina Makarova. She was barely twenty when she was employed by the Nazis, and she personally gunned down hundreds of people. Before executions she put on a children's carnival mask. If you see her, you die. But why does she keep killing?