Young Nastya brings home a tutor. But her mother is not happy with her daughter’s desire to study. A suspicious woman sees a hidden motive in the relationship between the girl and the teacher: Nastya was raised without a father and has now fallen in love with her mother’s peer: an educated, impressive man. The mother is ready to break off the shameful relationship at any cost: she does not disdain scandals, blackmail, or hysterics. But if she knew what secrets her daughter had from her...

In an ordinary industrial Soviet town, notable only for presence of a radio-telescope, people start behaving strangely, in a robotic manner, while assuming geometry-inspired aliases and organizing into a new hierarchy. The phenomenon spreads via a device of alien origin, called “the mediator”, capable of implanting extraterrestrial minds into human bodies. The aliens are bound by limitations of the terrestrial technology, having to use the means at the disposal of humans to prepare the grounds for the full-scale invasion. With “the mediator" being unable to subdue minds of children, lunatics, geniuses, and rebels, a struggle over the fate of the town and the human civilization ensues.