On her tenth birthday, tomboy Sophie learns she is the Guardian of a magic gateway between our world and the Shadow Woods. She must keep the human world safe from mischievous goblins, sprites and elves. It's the turn of the Spider Gnomes, gruesome man-sized spiders who make their webs in the trees of the Shadow Woods, to do battle with the Guardian. When the whole town becomes infested with spiders, Sophie and Sam realise something is seriously wrong, and the daring duo enter the Shadow Woods to investigate. During a terrifying encounter with these eight-legged Shadow Creatures, Sam gets bitten and starts acting very strangely! It doesn't take long for the pair to realise that the Spider Gnomes' fangs carry a poison that turns their victims into spiders themselves! Can Sam find the antidote before it's too late, and can Sophie figure out the strange clue before the spiders invade the town, find the gem and deliver it into the horrid hands of King Ug?