When thirteen year-old goth girl named Cassie (Emily Osment) moves into a new neighborhood with her family and starts pulling spooky pranks on the popular kids, the appearance of a mysterious books finds events taking a truly terrifying turn. Cassie isn't comfortable in her new surroundings, and feels rejected by her new classmates. Frustrated, she launches a tireless campaign to frighten the wits out of the entire student body as well as her younger brother Max (Alex Winzenread). With Halloween just twenty-four hours away, Cassie discovers an odd little book entitled "The Evil Thing." Despite the warning that implores owners never to read the book aloud, Max demands to hear the story and as a result, Cassie begins reading. Curiously, the story begins in the darkened woods behind their home, and soon introduces a mysterious stranger who may alter the course of the young sibling's lives.