The Mumins have already had to change their home before, and Mumipapa is a true wanderer. And so, toward the end of summer, he decides that a quiet life in the Valley isn’t for his restless nature. He wants to live on an island with a lighthouse in the middle of stormy seas and help ships find the right way. The family sets off on the journey.
At first, the lighthouse seems cold, empty, and unfriendly. But that impression is deceptive. Mumimamma can create coziness even on bare rock, and the island has enough mysteries, worries, and the power of the sea to last a long time.