In an attempt to earn their Sparrow Scouts botany badges, Hilda, David and Frida make a surprising discovery when they search for a rare plant.
Hilda, David and Frida have gathered at Hilda’s house to try and earn their botany badge by collecting specimens of 10 plants. It’s currently raining, but the forecast by Victoria Van Gale correctly predicts the rain will end in five seconds, which it does.
The friends head out to the park and quickly find some of the plants they need, but Hilda’s would rather seek out some rare specimens instead of settling for what is essentially just weed. She suggests trying to find a Blue Nettle. To Frida’s surprise, David admits he saw this plant, but he doesn’t want to go near it since it’s haunted. Nevertheless, he leads his friends to the location. There, Hilda discovers what David heard are not voices of ghosts, but Elves (which are still invisible to David and Frida). The Elves don’t take kindly to the 3 kids however and attack them, with David being taken captive.
Hilda and Frida rush back to Hilda’s house, where Frida fills out the paperwork so she can see Elves. Alfur is surprised to learn there are other Elves in Trolberg, and realizes they must be the lost clan of the Northern Counties. He tells Hilda and Frida that in the time of the first elves two families, the Bragga and the Aldric, met to execute a real estate contract for a plot of land. They succeeded after many trials, but when they brought the contract to the king, it turned out the Bragga had signed it only twice instead of three times. In those days, this was considered high treason, and the Bragga were banished from the Northern Counties, while the plot of land remains unused to this day as No Elf’s Land. But now that the descendants of the Bragga have finally been found, Alfur hopes he can settle the ancient conflict by getting the Bragga to sign a contract that will end their exile.
Unfortunately, the Bragga refuse to sign the contract since they swore off any form of paperwork due to the incident with the old contract. Worse; Bartell recognizes Alfur as a member of the Aldric family, and demands he pays for his families crimes by fighting all ten Bragga Rabbit Warriors. Including Agnes. Hilda agrees to fight alongside Alfur, but Frida interferes and offers to try and find a loophole in the contract instead. Bartell gives her one day and promises to give Frida a Blue Nettle if she succeeds, but they will keep David as a hostage to ensure Frida comes back.
Back at Hilda’s house, Frida discovers the contract contains an escape clause; it’s rendered void if destroyed by the fire of a Lindworm. Alfur is against the plan since Lindworms are rare and paper work averse, but the girls see no other option. They go to the library, and learn there that only one Lindworm still lives in Trolberg; on a very small island in the bay. In the harbor, Alfur instructs Hilda how to summon a water spirit by blowing on a conch shell. It works, and the water spirit gives them a ride to the island. Meanwhile, David gets along quite well with the Elves.
On the island, the girls and Alfur find the Lindworm asleep in the middle of her garden. Hilda tries to hold the contract close to the Lindworm’s nose as she exhales fire, but she steps on a branch and wakes the creature up. The Lindworm is quite angered to see another elf that wants to get out of a contract, and threatens to eat the humans to make it clear she is done burning contracts. Alfur quickly offers to give the Lindworm something in return, and Hilda follows up on this by promising the Lindworm the plants they found earlier that morning. Lucky for them, the Lindworm is greatly interested in urban flowers, and agrees to trade them for her destroying the contract.
With their mission completed, the girls and Alfur return back to the Bragga and show them the burned remains of the contract. Bartell has mixed feelings about his exile being over though, since the Bragga got quite attached to their home in Trolberg. He gives No Elf’s Land to Alfur. That night, the kids and Alfur celebrate the happy ending with the Bragga.