As the valley evacuates under the threat of volcanic eruption, Moomintroll helps Snufkin on a perilous quest to return a lost fire spirit to her home.

In an attempt to set a good example for his family, Moominpappa becomes a changed Moomin when he decides to get a job. But all is not what it seems.

When Moomintroll gets his wish to be free of the troublesome Little My, he soon comes to regret it.