Belka and Bertha could not imagine life without each other since childhood. The girls exchanged dresses, toys, becoming girls - perfume, image, lovers. But now the time has come to change destinies. The eccentric Bertha, having killed her husband in a fit of rage, easily and recklessly places the responsibility on the sacrificial Belka. And she, loving and pitying her friend, goes to prison instead. Only there, among the dregs of society, in a dirty, smelly cell, does she come to a clear understanding that she was basely and deliberately set up...