The book is published both as paperback and hardcover.
Hilda and her mum have settled into their new home in the city of Trolberg. Pining for her magical friends and the wonder filled wilderness, Hilda is finding it hard to fit in, especially at school. But when Hilda makes a new friend, she soon begins to uncover some surprising secrets…Perhaps this concrete labyrinth is a place where wonderful and magical things happen too?
Hilda lives in Trolberg now, but finds it hard to fit in. She misses the wilderness, has trouble paying attention in school, and has become the favorite target of class bully Trevor. The only kids she occasionally speaks with are Frida and David, but they are not quite friends.
In three days, Trolberg will host its annual Bird Parade, and Hilda’s class has been chosen to decorate a float. The class will also have to prepare an exhibition for parents night titled “wonderful Trolberg”. Ms. Hallgrim divides the class in pairs of three for the project, and Hilda ends up with Frida and David. Frida suggests they go to the Gorill Gardens bell tower to scout the city for rare plants they can use in their exhibition, and on the way there Hilda tells them more about her life in the wilderness, which fascinates Frida but scares David. Hilda spots a place with rare, Blue Nettle at the city wall on the outskirts of the town, and convinces Frida and David to go get it tomorrow. Before they head home, Hilda spots Trevor and his friends attacking birds with rocks. A raven gets hit and when Hilda rushes to his aid, she finds out the bird can speak. Trevor hears it too, and chases after Hilda as she runs off with the raven. Hilda is able to shake him off at the train tracks. Back at her house, Hilda introduces the raven to Twig and Alfur. The Raven has lost his memory when he was hit by the rock.
The following day, Trevor asks Hilda about the raven but she tells him nothing. After school, she, Frida and David go to the place where she saw the Blue Nettle. Once there, they find themselves under attack from a group of wild elves. Alfur, who was with Hilda, recognizes them as the lost clan of the Northern Counties, who got banished long ago after failing to properly sign an important contract between them and the Aldric family (which Alfur belongs to). The children are taken captive, and the clan leader, Bartell, demands the old conflict to be settled once and for all with a fight. Hilda however is able to negotiate an alternative; if they can get the faulty contract that got the Bragga banished to be burned by a Lindworm, it will be rendered invalid and absolve the Bragga of all blame. Bartell agrees if David remains as a hostage, and Hilda finds the Lindworm before sunset. After some research at the library, Hilda, Frida and Alfur discover there is a Lindworm still living on Cauldron Island in the fjord. To get to the island, they ask a Water Spirit for a ride. When they find the Lindworm, she had no interest in helping them and wants to burn the three for disturbing her, but changes her mind when Frida offers the Lindworm some of the plants she has already collected. Once the contract is destroyed, Hilda, Frida and Alfur return to the Bragga. David is released, and the children get their blue nettle, but the Bragga prefer to stay in Trolberg despite their exile being over. Frida and David however are not happy about getting dragged into this adventure, which confuses Hilda. David even leaves without thanking Hilda, only stopping to pick up some rocks.
Hilda continues to try and help the Raven remember anything. She feeds him some of her blue nettle, which is said to be good for the brain. The raven remembers he is important, and something about a gigantic statue. The following day, at school, Hilda gets into an argument with her teacher Ms. Hallgrim about the school float, which depicts Edmund Ahlberg with a dead troll at his feet, which Hilda finds cruel. Ms. Hallgrim also informs Hilda that Frida and David’s parents complained about her, and she is thus taken from their group for the exhibition project. Trevor meanwhile still has his mind set on proving the raven can talk. He drops by at Hilda’s house when she is not there, and lies to Johanna that he is a friend of Hilda send to pick up the raven. When Hilda hears what happened, she realizes Trevor wants to use the raven for his exhibition at school tomorrow.
Hilda asks Alfur to help her free the Raven. She brings the Nittens from Angelina with her as her project. Frida and David have made an exhibition with the plants they gathered and some of David’s rocks, and as expected Trevor brings the Raven. The bird refuses to talk however, which angers Trevor. Hilda can’t do much about it right now since Ms. Hallgrim is expecting her to cause trouble again, and thus keeps an eye on Hilda. When Ms. Hallgrim opens the exhibition with a film about Trolberg’s history, Hilda tries to free the Raven. The film also mentions the history of Bird Parade, and when she sees this Hilda realizes the Raven is none other than the Great Raven who visits Trolberg once a year. The parade is that night, and the Raven can’t appear if Trevor keeps him captive.
Hilda’s plan to free the Raven is further complicated when one of David’s rocks turns out to be a baby troll rock. This puts David at risk since bringing a troll into Trolberg can get you send to jail. With two problems to take care off, Hilda apologizes to David and Frida for endangering them, and with great effort convinces them and her mum of the situation. Frida agrees to try and free the Raven while Hilda focusses on the Troll. The troll escapes from the classroom and seeks shelter in the ventilation shafts. Outside the school, an adult troll shows up to look for her lost child. When the schools principal, Mr. Magnusson, sees the adult troll, he wants to raise the alarm, but Hilda stops him, fearing it will cause panic (and that the trolls will be hurt). She offers to catch the baby troll. Magnusson gives her one minute to succeed. With help of a fishing net, Hilda is able to get the baby troll out of the school’s ventilation shafts, and returns it to the mother. The two trolls leave, but the adult troll stops briefly to smash the float depicting Edmund Ahlberg.
During the chaos with the trolls, Trevor has fled the school with the captive Raven. Hilda, Frida and David rush after him, and try to locate Trevor among the large crowd that has gathered for the parade. Frida suggests they use a nearby bell tower equipped with a searchlight. It works, and they spot Trevor as he heads towards the river. Hilda uses her scarf to slide down a telephone wire in an attempt to catch up with Trevor, but she falls. Her fall is broken because she lands on top of the float of the Trolberg Trampolining Club. She and David finally catch up with Trevor at the Bronstad Lane Footbridge. Rather than lose the Raven to Hilda, Trevor throws the still caged bird in the river.
Hilda dives after the Raven, is able to free him from his cage, and gives him some more blue nettle. This finally restores the Raven’s memory. He transforms to his true, gigantic size and takes Hilda for a flight. He admits to Hilda that he is actually just a Thunderbird, and doesn’t really bring good luck like the people of Trolberg think, but he still likes to attend the parade thrown in his honor. Now that he is here, the parade can begin. The Great Raven drops Hilda off with her mom. Together they watch the parade. Hilda concludes that maybe she can get used to Trolberg after all, and feels that she, David and Frida will friends for life from now on.
- Johanna (called “Mum” in this book).
- Trevor’s friends
- Principal Magnusson
- Ms. Hallgrim
- Edmund Ahlberg (mentioned)
- The Librarian
- Victoria Van Gale (mentioned)
- Sigrid Spenstig
However, it takes quite a few liberties with the episodes it adapts, most notably the order in which the events take place. Other notable differences include:
- In the animated series (and also the graphic novel), the Great Raven loses and regains his memory within a day. Here, he spends several days as an amnesiac. He also doesn’t need the blue nettle to help regain his memory.
- While the animated adaptation already made him into a worse character than he was in the graphic novel, Trevor is depicted as an even bigger bully in this book, constantly picking on Hilda and being more manipulative.
- In the animated series, Hilda officially becomes friends with Frida and David after joining the Sparrow Scouts. Here, they meet each other in school.
- In the animated series, Hilda, Frida and David want to collect the Blue Nettle for a Sparrow Scouts badge. Here, they collect it for their exhibition at school.
- In the series, only David is taken captive by the Bragga.
- In the series, David finds the troll rock while guarding the entrance to a Vittra tunnel. Here, he picks it up after being freed from the Bragga.
- Twig does not come with Frida and Hilda to Cauldron Island in the series.
- While Frida and Hilda have a falling out in the animated series, there it is due to Frida losing her favorite book and Hilda’s failed attempts to get it back, not because of the adventure with the Bragga.
- The book doesn't reveal how the mother troll got into Trolberg, other than a brief remark from David that the wall near the Blue Nettle is quite fragile and a Troll could probably break through. The series shows her getting in through the Vittra tunnels.
- In the series, the troll destroys a statue of Edmund Ahlberg instead of a parade float.
- Principal Magnusson never finds out about the baby troll in the series.
- In the series, David and Frida don’t participate in rescuing the Great Raven, since they are with the Sparrow Scouts on their float and haven’t befriended Hilda yet at that point.