An engineer and his 5-year old son Rasmus are kidnapped by a group who wants to get their hands on the engineer's latest invention. Three kids become witnesses to the kidnapping and decide to follow the kidnappers to an island and attempt to make a rescue.
| Actor | Role |
|---|---|
| TTotte StenebyAnders | Anders |
| JJosefin ÅrlingEva-Lotta | Eva-Lotta |
| MMalte ForsbergKalle Blomkvist | Kalle Blomkvist |
| WWilliam SvedbergRasmus | Rasmus |
 Pierre LindstedtNicke | Nicke |
 Rolf DegerlundPeters | Peters |
 Patrik BergnerBlom | Blom |
 Claes MalmbergPoliskonstapel Björk | Poliskonstapel Björk |
 Jan MybrandProfessorn | Professorn |
| VVictor SandbergSixten | Sixten |
 Johan StattinJonte | Jonte |
| BBobbo StenebyBenke | Benke |