This time, they travel on holiday with Aunt Thea to Summer Island. There they meet Eddy who is an expert on all the challenges they can face on a magical island. It is rumored that a sea worm has been observed in the fjord, and it will not be long before the energetic sea worm expert Blegen shows up, with his strange devices and instruments. It will be an exciting summer holiday with friendship put to the test, exploration in nature and the hunt for the mysterious sea worm.
Unfortunately the movie Twigson and the Sea Monster is not yet available on HBO Max.
| Directing | Tove Undheim | Director |
| Production | Finn Gjerdrum | Producer |
| Production | Stein B. Kvae | Producer |
| Editing | Margrete Vinnem | Editor |
| Writing | Anne-Cath. Vestly | Book |
| Sound | Erlend Mokkelbost | Music |
| Sound | Erik Johannessen | Music |
| Camera | Łukasz Zamaro | Director of Photography |
| Writing | Tove Undheim | Writer |
| Production | Erik Poppe | Executive Producer |
| Production | Jan Petter Dickman | Executive Producer |
| Production | Stein B. Kvae | Executive Producer |
| Writing | Lars Kilevold | Story |
| Costume & Make-Up | Miriam Lien | Costume Design |
| Costume & Make-Up | Isabella Leikanger Mork | Costume Design |
| Art | Åsa Nilsson | Production Design |
| Sound | Fredric Vogel | Sound Designer |
| Writing | Aksel Kielland | Writer |
| Production | Finn Gjerdrum | Executive Producer |
| Costume & Make-Up | Grethe Gunn Solberg Hansen | Makeup Artist |
| Production | Nicholas Sando | Line Producer |
| Production | Mia Jensen | Casting |