It's been five years since the dragons and Vikings made peace. Everything's okay for Hiccup and the gang, until an almost fatal fire caused by himself sends him away from Berk. He winds up in Arendelle where he meets Elsa the new Queen of Arendelle a polite, reserved girl with a cold secret. The friendship between them starts to spark. Love at first sight. On the day of her coronation she reveals her secret of ice powers. Full of fear runs away her kingdom and her sister, trapping it in an eternal winter.

Karli is the daughter of Hiccup and Elsa. She was born half Mortal Half Immortal. She's a Werewolf, like her father. Karli has been living her life, disguised as an ordinary School girl. Her whole life, her father taught her to always keep herself safe from humans who want to get rid of Werewolves. She meets Hayden- a 17 year old boy in her school with a secret like her, and unknowingly falls in love with him. When her father gets revealed to the FBI and he's been tested for a Werewolf Virus, which causes him to feed and kill on other Werewolves, Karli's only chances with him is to find a Cure for the virus, before he wipes the entire Werewolf Species.