The film tells the story of the Moomin family's preparations for winter and their hibernation, interrupted by unexpected events: the appearance of the mischievous Nibling, a visit to Too-Ticky, who lives by the sea, the adventures of Little My, rescued by Moomintroll, the exploits of the Hemulen, a sports enthusiast, and so on. The story ends with the arrival of spring, the awakening of all the inhabitants of Moominvalley, and the return of Snufkin. The film is based on episodes of the television series "Moomin Stories".
| Actor | Role |
|---|---|
 Stanisław KwaśniakNarrator (voice) | Narrator (voice) |
 Michał SzewczykMuminek (voice) | Muminek (voice) |
 Andrzej HerderTatuś Muminka / Paszczak (voice) | Tatuś Muminka / Paszczak (voice) |
 Małgorzata RogackaToo-Tiki / Filifionka (voice) | Too-Tiki / Filifionka (voice) |
| DDanuta KłopockaWiewiórka / Gryzilepek (voice) | Wiewiórka / Gryzilepek (voice) |
| MMarek KołaczkowskiWłóczykij / Ynk / listonosz (voice) | Włóczykij / Ynk / listonosz (voice) |
 Alicja KrawczykMała Mi (voice) | Mała Mi (voice) |
| BBarbara BorkowskaMama Muminka (voice) | Mama Muminka (voice) |