Moomintroll and his friends find a magical and mysterious hat. While fun to begin with, they soon realise that the hat is dangerous.

In his desire for more independence, Moomintroll pushes Moominmamma away. But he soon becomes jealous when she finds a new outlet for her motherly love.

Sniff learns that friends are far more important than possessions when he tries to make himself rich by defending the Groke in Moominpappa's impromptu court case, and the Hobgoblin finally arrives in Moominvalley.