This article is about one of the books from the Hilda series of graphic novels.
You may be looking for the Netflix-exclusive television series of the same name.
Picking up where the previous story left of, Hilda is now a troll child living in a cave in the Stone Forest, while Baba is a human child living with Johanna. Baba’s mom explains to Hilda that she wanted a better life for her daughter, and that she thought Hilda would like being a troll more. Hilda however panics and runs out of the cave, but since it’s day the sunlight instantly petrifies her.
In Trolberg, Johanna has great trouble controlling Baba. When Tontu sees Baba, he concludes they are dealing with a changeling. Johanna, Baba and Tontu thus set out for the wilderness outside Trolberg to try an find Hilda. They search all day till it’s almost sunset, when they are found by Erik Ahlberg, the leader of the Safety Patrol. He tells Johanna that there are more trolls than ever in the area, and insists she goes back to Trolberg. He bells a petrified Troll.
That Troll is none other than Hilda. When the sun sets she awakens, and since she’s a troll now the ringing of the bell hurts her. She manages to get rid of the bell. Baba’s mom comes for her, but Hilda manages to elude her, and in doing so finds a huge cave with dozens of bells hanging from the ceiling of the entrance. Inside she finds a gigantic troll with no eyes, who calls himself Trundle. He tells Hilda that there is a way she can become human again, which he will show her if she helps him. He also assures her Baba’s mom means no harm, since she considers Hilda her daughter now. Hilda reluctantly returns to Baba’s mom.
That night, in Trolberg, ranger Ahlberg presents the Safety Patrol’s latest weapon for hunting trolls. Johanna realizes Hilda is in danger if the Safety Patrol decides to engage the Trolls in a fight. In the mountains, Baba’s mom tells Hilda that the trolls stay close to Trolberg, since it used to be their home before the humans came.
The following day, Johanna and Baba resume their search for Hilda. When night falls they see Baba’s mom and try to talk to her, but are forced to flee when other trolls attack them. That same night, Hilda returns to Trundle. He wants Hilda to remove the bells that are keeping him trapped in the cave. Hilda takes some time to think about the offer. Baba’s mom shows Hilda more about Troll society, including the ruins of the castle of the Mountain King; a giant troll that once tried to rally all trolls into attacking the city, but was defeated. For a moment, it seems Hilda actually begins to appreciate her new life, since being a Troll gives her abilities above those of a human and she is free to roam the wilderness again. But she still longs for her home and convinces Baba’s mom that she should undo the spell put on Hilda. Unfortunately, she can’t. Seeing no other way out, Hilda decides to help Trundle. She uses pillows (which she steals from a Troll's treasure collection) to silence the bells, and can thus safely remove them.
After her narrow escape from the Trolls, Johanna sees no other option than to ask Ahlberg for help. Meanwhile, Trundle sends Hilda on another assignment to bring him a big, red orb, hidden in the ruins of the castle among the treasure of the Mountain King. When Hilda touches the orb, it shows her a vision in which she ends up in a strange-looking city inhabited by tiny trolls. When the trolls attack her, a giant creature resembling her mom bursts out of the ground and destroys the entire city. When the vision ends, Hilda leaves the ruins, but is seen by a massive, bearded troll. She panics and flees the cave with the orb, chased by the troll. Outside, she is spotted by her mom, Baba and Ahlberg. Ahlberg tries to stop the troll, but his torch is too weak to harm the giant creature and he is easily defeated. When the troll turns his attention on Johanna next, Hilda attacks the Troll. She is saved when the troll accidentally steps on Johanna's car, loses his balance, and falls into a ravine. Hilda and her mom are reunited.
With her mom, Baba and Tontu, Hilda brings the orb to Trundle’s cave, where both Baba’s mom and Ahlberg await them. Ahlberg considers Baba’s mom a threat and tries to shoot her, but is stopped and disarmed by Johanna. Now that Hilda and Baba are both back with their true mothers, the spell is lifted and they become their old selves again. All seems well, until Baba’s mom notices the bells are gone. She informs Hilda that those bells were put there by trolls to keep Trundle a prisoner, because he is the dreaded Mountain King. The orb Hilda just returned to him was his missing eye.
With his eye restored and no more bells, Trundle breaks out of the cave, rallies the other Trolls, and attacks Trolberg. He easily breaks through the wall and lets the Trolls into the city. The Safety Patrol arrives to fight off the attack. Hilda realizes the scenario is similar to what she saw in her vision, and understands there must be a gigantic Troll underneath Trolberg, who will rise up to defend her fellow Trolls if the Safety Patrol attacks them.
The Safety Patrol deploys their new weapon, a giant version of the torch guns, against Trundle. Trundle’s body petrifies and crumbles, leaving only some rocks and his red eye. Hilda tries in vain to convince Ahlberg to stop the attack. When he won’t listen, she takes the red orb and throws it at Ahlberg. This causes Ahlberg to see the same vision Hilda herself saw, and he finally understands what is at stake. He orders the Safety Patrol to stand down and let the trolls into the city.
The bearded troll also shows up again, and introduces himself as Trundle’s brother. He confirms Hilda’s story; there is a giant troll underneath the city. Amma, the mother of all Trolls. She has been laying dormant for centuries in order not to hurt the humans who build their city above her, but Trundle tried to provoke her into rising up to defend her children. His plan has failed, and Trolberg is safe. And now that the Trolls are in the city, they can finally hear Amma’s voice again, and guided by her they all sprout plants all over their bodies.
The story concludes with Hilda narrating how, from that moment onwards, the city would hold The Night of the Trolls every year, where Trolls are allowed to go into the city to hear Amma and get a chance to bloom. Baba continues to come and visit Hilda at her house so she can spend some time as a little girl, and sometimes Hilda visits Baba and her mom so she can spend a night outside in the wilderness.