In a provincial town, a dangerous maniac appears, hunting women. On his account already several victims. The police, alarmed by the panic in the city, understand that it is necessary to act somehow. And the innocent people were captured, one of them is already waiting for the execution. Investigator Ignatov leads this case. He has to deal with lawlessness and arbitrariness of the investigating authorities, because of the mistakes of which the innocent were convicted, and the real criminal was never found.

During the war, the Germans exported breeding horses from Russia, among which was Ermakov’s favorite. After the war, he managed to find her and return her to Russia, but the tribal certificate was lost. And now, forty years later, the granddaughter of this horse - the magnificent race mare Secunda - is being sold for pennies at an international auction to a certain Baron von Ritter. Ermakov guesses about the true owner of the “lost” document and, in the end, returns it to himself.