In "Chapter 7: The Lost Clan", Hilda convinces Frida and David to try and find the Blue Nettle for their Sparrow Scouts Botany Badge. Since the plant is so rare, it will most likely grand them the badge with golden wings. David admits that he saw some Blue Nettle in Gorrill Gardens, but is afraid to go there again since the place is supposedly haunted. In reality, the Blue Nettle turns out to be next to the village of the Bragga Family; an exiled group of Elves.
At the end of the episode, after Hilda and Frida manage to end the Bragga's exile, the Bragga allow them to take a Blue Nettle.
The adventure involving the Blue Nettle and the Bragga also happens in "Hilda and the Great Parade", except in this story Hilda and her friends want the plant for their Wonderful Trolberg exhibition at The Ahlberg School.
The book further reveals that the Blue Nettle is good for the brain; a fact that was not in the animated series. After getting their hands on a blue nettle each, Hilda sacrifices hers to help The Great Raven, who has lost his memory after getting hit by a rock, and is now staying at her house. Thanks to the Blue Nettle, Raven is able to remember that he is important, and that the reason why involves a large statue. Near the end of the book, when Hilda saves the Raven after Trevor throws him in the river, she gives the Raven some more Blue Nettle that she took from Frida and David's project. This second dose finally restores the Raven's memory entirely.