Elena is the head of the kindergarten. Her life proceeds smoothly and happily: she is married, the daughter of Light is smart and beautiful. The girl needs to tighten up chemistry, and Elena finds a senior student of a chemical technology university, Natalia, through the website. She copes with her duties perfectly. Moreover, Sveta and Natalia become best friends — the girl dotes on the tutor, trying to imitate her in everything. Elena is slightly concerned about Natalia's influence on her daughter, but she likes the result of the lessons, and she decides not to interfere with their close communication. If not for one thing: for some time Elena began to notice that her husband was not breathing evenly to the student. And she does not behave modestly, clearly seducing the student's father. Unable to stand it, Elena makes a scandal and expels Natalia out. Upon learning about this, Sveta becomes hysterical. She idolizes her older friend, not imagining life without her, but now the offended Natalia will not want to know her. Elena is already ready to back down for the sake of her daughter and is even ready to apologize to Natalia for her rudeness, but she disappeared without a trace. Sveta is depressed, and Elena Ivanovna, after hesitating, decides to go to the institute dormitory to find Natalia there. However, she is told that such a student graduated from the institute and left. Fear creeps into Elena's soul. Who is Natalia then? Who did they let into their house?