A simple phrase: “Don’t get nervous, everything will be fine”—can instantly drive a person into a rage. But for the old friend of Ivan Nikiforovich and Tania Sergeeva, it’s worth searching for the fifth corner. A special brigade was approached by Fyodor Volkov, a big boss of an office that’s better not to mention out loud. He had a secret wife, Lida Popova. They hid their relationship so that nobody could use Popova as a lever to pressure Volkov. But one day Lida called her husband and asked him to come to the village of Kosyukhino urgently. Fyodor rushed to the summons, but found Lida dead on the floor in an abandoned cottage. At that moment, noise came from the street—forcing Volkov to hide for a while in a cupboard. When he came out, he saw with horror that the body had disappeared without a trace. To ensure that information about the terrible incident reached the “office,” Volkov turned to private detectives. Tania and her colleagues took up the investigation with enthusiasm. Sergeeva found everyone: both Lida and those who crossed her out of life. But all her ideals collapsed when she learned their names…