Svein's best friend is a fancy rat named Halvorsen who goes missing during a pet contest, leading to chaos with newspapers reporting a rat invasion. To avoid losing both Halvorsen and the competition, Svein must work to keep his parents unaware of the situation.
| Actor | Role |
|---|---|
| TThomas Saraby VatleSvein | Svein |
| LLuis Engebrigtsen ByeDan | Dan |
| CCeline Louise Dyran SmithMelissa | Melissa |
| BBenjamin GulliKim | Kim |
 Miriam SognMother | Mother |
 Aslag GuttormsgaardFather | Father |
| RRasmus HoholmMagnus | Magnus |
 Jan Gunnar RøiseTrumma | Trumma |
 Marie Louise TankHeadmaster | Headmaster |
 Håvard LilleheieLecturer | Lecturer |
 Bjarte HjelmelandSnorre | Snorre |
| JJanny Hoff BrekkeDani Dyrebutikk | Dani Dyrebutikk |
| SSeverin EskelandJohnny | Johnny |
 Steinar SagenBlind Man | Blind Man |
| TTina LøvbergMonica | Monica |
| NNinni A. BorgeCamilla | Camilla |
| HHelene GystadRotta | Rotta |