Fablehaven is a fantasy book series written by Brandon Mull. The story follows siblings Kendra and Seth Sorenson as they discover a secret magical preserve for mythical creatures. They learn about the importance of protecting these beings and the challenges that come with it. The series explores themes of bravery, friendship, and the balance between good and evil. As Kendra and Seth navigate various adventures, they encounter a range of magical creatures, including fairies, demons, and goblins. The books emphasize the significance of family and the responsibilities that come with discovering hidden worlds.