When Moomintroll unexpectedly wakes up early from his winter hibernation, he finds himself completely alone for the first time, in a world he barely recognizes. The familiar landscape of Moominvalley is now cloaked in the frosty veil of the Lady of the Cold. Initially seeking someone to care for him and longing to banish winter, young Moomintroll reluctantly embarks on a journey into the unknown, learning to forge new friendships and help those in greater need than himself.
