Two schoolboys, Kolya and Fima, follow a mysterious strange lady to an abandoned house. When they enter the house, they find no trace of the stranger, but in the empty basement Kolya discovers a secret door that leads to a room with a technical device in it. Curious Kolya starts pressing some buttons and activates the device that "transfers" him to another place.

Having reached the space port, Kolya unsuccessfully tries to get a ticket for an interplanetary flight. However, by joining a group of pupils who escort their project satellite to the launch, he manages to enter the transit area. There he witnesses how two service workers are stunned and then impersonated by two shape-shifting aliens that have emerged from a crate.

Alisa is in hospital, recovering after the accident and faking amnesia in order to hide her origin. However, she talks about dolphin languages and exotic fruits. Her roommate Yulya thinks she just makes up those stories but likes her anyway. In the night, Kolya and Fima enter the basement of the abandoned house but the entrance to the time machine is blocked.

Alisa is admitted to school, excels in English class and also receives letters from classmates. Fima, triumphant that his predictions have come true so far, wonders whether Alisa will try to eliminate Kolya as witness if he gives her the myelophone. He explains to Kolya the danger of creating alternative timelines by using knowledge from the future.

Alisa runs after the pirates. Yulya finds the myelophone in her lunch bag. Alisa uses it telling her two men are carrying an unconscious boy to the abandoned house. The children rescue the boy, and the pirates are finally captured.