One day in August, Moominpappa realized that most of all he wanted to live not in the Valley, but on an island with a lighthouse, among the raging sea. When the boat with the Moomin family sailed to the island, it turned out that no one was waiting for them there, the lighthouse was closed, the only neighbors were the gloomy Fisherman, and in general a more boring place could not be found. But it soon became clear that the island holds so many secrets, mysteries and surprises that there really is enough adventure for a whole year.