- Everyone knows the Moomins sleep through the winter. But this year, Moomintroll has woken up early. So while the rest of the family slumber, he decides to visit his favorite summer haunts. But all he finds is this strange white stuff. Even the sun is gone! Moomintroll is angry: whoever Winter is, she has some nerve. Determined to discover the truth about this most mysterious of all seasons, Moomintroll goes where no Moomin has gone before.