The Great Patriotic War. Soviet intelligence officers led by Sergei Skorin and Andrei Losev are trying to track down a well-trained sabotage group that is staging large-scale sabotage in the rear of the Red Army on the eve of the Battle of Kursk. Andrey and Sergey are brothers, but there has been a conflict between them for many years. Andrey does not trust Sergei, because he suspects that his brother has been turned upside down.

Oleg's young beautiful daughter Alyona falls in love with his once best friend and peer, Anton.Oleg does everything he can to prevent the union of his only daughter with an immoral type like Anton, whose past makes him the worst candidate for son-in-law in the world.