One week after the tragic death of Anatolii Ivanovich, his son Sergei survives a new shock. He receives a letter from his mother who was considered deceased long ago.
The mother tells Sergei that his father has left her, hopelessly ill with tuberculosis, almost thirty years ago. However, she lived out, survived numerous troubles over the many years and finally decided to find her son. Sergei is happy. He brings the mother to his place. However, her relations with the daughter-in-law don’t work out.
Sergei’s wife does not trust Valentina, she thinks, that there is something strange behind the arrival of that woman.
Olga tries to find out what has happened in Korostylevs’ family thirty years ago. She goes to the city where Sergei spent his childhood. The truth she is gradually discovering turs out to be a real dynamite barrel.
Olga understands that she has to save her family as soon as possible. Will she be able to leave this city alive?