With their father away, Nonni and Manni meet Harald, who brings news of their father's death. Harald makes a good impression on the family, but Magnus is threatened by his charisma and attempts to frame him for a murder he didn't commit.
With Harald on the lam for a crime he didn't commit, Nonni suggests to Harald that Julli can help him find a secret place to hide. Later, the boys leave home without telling Sigrid, worrying her which prompts Magnus to form a search party.
After a harrowing night at sea, the boys make it home safely. Magnus tries to pressure Sigrid into marrying him, but she dodges the subject. With Julli's help, Harald finds a new hiding place, but is challenged by new dangers in the wild.
Sverrir continues to blackmail Magnus, and the magistrate becomes suspicious. Magnus hires men to watch the boys at all times, which upsets Sigrid. Nonni sets off to find Harald but gets caught in a blizzard on his way to the mountains.
Soon after Nonni recovers from the blizzard, the magistrate holds an inquisition. Magnus offers a reward to the townsmen for the capture of Harald. Sigrid considers Harald's innocence and a plan is formed to set Magnus up to admit guilt.
Sverrir comes clean to the magistrate with his evidence against Magnus. The boys seek out Harald in the mountains but Magnus captures them and takes them hostage. A volcano erupts, and Magnus and Harald face each other in a fiery showdown.