Dereck, is a normal thirteen-year-old boy who has agreed to take care of his five-year-old sister, Jessie, while their mother is away overnight. As the big brother, he intends to keep his sister safe, taking on the role of their dad who died in a car accident the year before. Derek loves his sister, but her constant need of his attention is starting to get on his nerves. However his mom is always reminding him to spend time with his little sister. The only thing Jessie wants Dereck to do is read fairy tales to her, though he would prefer they do anything else like shoot bottle rockets or throw a baseball around. When Jessie takes a nap, a violent storm moves in, causing Dereck to stumble down the steps to the cellar of their home. When Jessie screams out for help, Dereck imagines a tree crashing through her window, trapping his sister in her room. Trying to run to his sister's rescue, he falls through the cellar floor and wakes up in Oz - an Oz filled with all the fairy-tale characters Jessie loves (and he hates) so much.