A beautiful summer day in Moomin Valley. Suddenly, a wasp stings Moomintroll, who falls ill and has to stay in bed. To cheer him up, Moominpappa recounts his youthful adventures; his misunderstood childhood, escape from an orphanage and his historic meeting with the inventor Hodgkins.

This winter is extraordinary; Moomintroll decides to stay awake to explore the winter instead of hibernating as usually. And winters are certainly totally different than he had imagined. Strangest creatures wander amidst the snowdrifts; midwinter darkness surrounds the Moominvalley, and on top of that, an eccentric guest is soon to appear. This guest requires many measures, and is called Christmas, Hemulen tells to a surprised Moomintroll.