"This brief novel tells the story of Sophia, a six-year-old girl awakening to existence, and Sophia's grandmother, nearing the end of hers, as they spend the summer on a tiny unspoiled island in the Gulf of Finland." -- Publisher's description.

After a disastrous helicopter ride through a thunderstorm, the entire Moomin family is stranded on a desert island...the very island their ancestors came from! They make the best of it, hunting for their supper, exploring mysterious tunnels, and salvaging items from a wrecked pirate ship (including the Mymble!), but their ancestors don't let them live in peace and quiet for too long.