When the volcano erupts, Spruce Creek overflows and floods all of Moominvalley and fills Moominmama's kitchen up with water. Soan almost the whole Moomin house is underwater, and the Moomin family has to take shelter in a very odd, big house which happens to float by. Moomintroll and the Snork Maiden get left behind in a tree, and Little My is washed away. Then the Moomins learn that their new house is really a theatre, so Moominpapa writes a play and puts it on. And everyone is reunited happily after their many adventures.
