Father, mother and Martusya Bobrenka live not far from the Zdvizh River. One morning, the joyful news about the upcoming addition to the family makes them think about a new home. Beavers have to look for a more spacious home. Martusya's life will no longer be the same as before: she is already an "adult" and must master her feelings, find a common language with new acquaintances, get used to the rules and study at the lyceum... Turtle Pelagia, Aunt Sova, Marena Dniprovska, Cancer Iraklii, sister fish Irynka and Darynka and everyone-everyone-everyone will help her!