Sixth-grader Kolya and his friend follow a mysterious woman to an abandoned house, where Kolya stumbles upon a time machine that transports him 100 years into the future, where he meets other time travelers who collect historical relics.

Kolya sees two shapeshifting pirates take the form of facility workers and tries to warn Pavel; the pirates impersonate Pavel to steal a mind-reading device called the "myelophone," and Kolya attempts to take it back from them.

Kolya and Fima evade the pirates, who followed Kolya back to 1984; Alisa, hospitalized after her traffic accident, pretends to have amnesia to throw off suspicion, but she eventually confesses her origin to her roommate, Yulya, who helps her escape.

Looking for the boy named Kolya, Alisa joins his school and Fima worries that she will kill Kolya once she gets the myelophone back from him; the pirates continue to stalk Alisa, who draws everyone's attention with her academic and athletic prowess.

After the pirates abduct Kolya, Alisa and the other children split up to track down both the pirates and the hidden myelophone before the pirates can coerce Kolya into giving up its whereabouts.