A peaceful summer day in the Moomin Valley is interrupted by a volcanic eruption. At the last minute the Moomin family finds refuge in a strange house. It turns out it's not an ordinary house but a theatre stage where the Moomin Family begins to write a play.

The story bases on four Finnish brothers, nicknamed 'the Eura Daltons' who received nation-wide notoriety for tearing gas pumps apart when they needed cash. The cast is an impressive one: the brothers are portrayed by Peter Franzen, Lauri Nurkse, Niko Saarela and Jasper Pääkkönen while their really evil father is played by Vesa-Matti Loiri, one of the grand old men of Finnish cinema.