About the book: year / On the day of the summer solstice, twelve-year-old Sergei and his girlfriend Natka decide to go to the Central Park of Culture and Leisure. On the same day, Sergei’s older sister, Ksenia, has a date planned with a certain Slavik. However, the mother of Sergei and Ksenia decides that it is dangerous to let the children go alone across the city and orders Ksenia to accompany her brother. An unwanted trip brings another surprise - Ksenia and Slavik unexpectedly become the same age as Sergei and Natka.