The plot of the Russian detective series "Son" revolves around a young teacher named Alexandra who has lost her child. Four-year-old Danya disappeared without a trace during a walk, and the police were unable to help the parents. Soon, Sasha's ex-husband, who had given up hope of finding the boy, also turned away from her. However, the woman does not lose hope of meeting Danya again. One day, she thinks she spotted her son in a news story on television. With her suspicions, she turns to the father of one of her students - a police major.