Based on a true story, these are the exciting events that occurred in the life of the smallest soldier - a hero of the Great Patriotic War, six-year-old Sergei Aleshkov. Sergei loses all of his relatives and is adopted by soldiers of the Red Army. The soldiers play games with Sergei in order to preserve his childhood, and he, in order to comply with this honorary title, becomes a true defender of the Motherland.