Meryl Curtis, her sister Flora, Sam Felton, and Alex Ray are chosen for a special research trip to the Silver Trail by their teachers. However, a simple school trip soon turns nasty. The kids never could have suspected that the Trail would be much less silver than it would be sinister. The mayhem begins when Sam's beloved husky, Howl, is abducted. The boys both suspect the same person: the one who's supposed to be guiding them. Their suspicions are further confirmed when Meryl finds a strange diary filled with letters written by their so-called guide, detailing her, her sister's, and her friends' lives. Aided only by a few mysterious forces called Eternal Spirits and a nature-loving inhabitant of the Trail, Ann Mason, the group must face clever, powerful enemies to save Silver Trail. That's only the beginning, though, as they soon discover an entire hidden world.