Hilda and the Mountain King

Detailed Plot Summary for YouTube
Hilda and the Mountain King picks up immediately after the season 2 finale, The Stone Forest, with Hilda waking up in the body of a troll due to a changeling spell cast by Trylla, who placed her baby Baba in Hilda’s place. Hilda, now a troll, flees Trylla but is petrified by sunlight outside the Stone Forest. Meanwhile, in Trolberg, Hilda’s mother Johanna discovers the human baby troll and, with the help of Tontu, realizes Hilda has been transformed.

At night, Hilda unpetrifies and meets Trundle, a massive blind troll imprisoned in a cave by bells. He offers to help her become human again if she completes three tasks. She reluctantly returns to Trylla, learning that trolls hear a mysterious call drawing them toward Trolberg. Back in the city, Erik Ahlberg imposes a curfew due to rising troll activity, and Frida and David protest a misleading safety video about trolls.

Hilda begins her tasks: delivering troll mead to Trundle and using stolen pillows to silence and remove the bells trapping him. She learns from Trylla about the Mountain King, a legendary troll who once tried to attack Trolberg. When Johanna and Alfur find the Stone Forest entrance, trolls block it, forcing them to flee.

Frustrated, Frida attempts a failed body-swap spell. Trundle then sends Hilda on her final task: retrieving a large red orb from the Mountain King’s ruins. Upon touching it, Hilda sees a vision of a giant troll resembling her mother looming over Trolberg. As she flees with the orb, she’s attacked by a bearded troll.

Meanwhile, Ahlberg, Johanna, Baba, Alfur, and Tontu arrive at the Stone Forest. Baba opens the entrance just as Hilda bursts out, chased by the bearded troll. A fight ensues—Ahlberg is knocked out, and the troll crashes Johanna’s car before falling into a ravine. Hilda and Johanna reunite and bring the orb to Trundle. Trylla appears, reuniting with Baba and reversing the changeling spell—Hilda becomes human again, and Baba a troll.

Trundle then breaks free, revealing the orb is his eye. Now able to see, he declares himself the Mountain King and rallies the trolls to attack Trolberg. In the city, Frida uses magic to connect with a troll and sees the same vision—of a colossal mother troll beneath Trolberg. Trundle destroys belltowers but is stopped by his brother, the bearded troll, whom he refuses to fight.

As the Safety Patrol prepares to attack, Hilda realizes the mother troll—Amma, the ancient matriarch of all trolls—will awaken and destroy Trolberg if provoked. When Ahlberg ignores her, she throws Trundle’s eye at him, forcing him to see the vision. He halts the attack.

The trolls gather peacefully around Amma, who lies beneath the city. Having slept for centuries to avoid disturbing humans, she is finally reconnected with her children, who begin sprouting plants. Ahlberg resigns, handing control to Gerda Gustav, who declares an annual “Night of the Trolls” for peaceful reunions.