Synopsis:Professor Goldman does not believe in ghosts. In fact he teaches a college course on how to debunk ghost stories using earth sciences. He is a mocking, arrogant professor who uses his authority to bully students and coerce co-eds into sex. His latest target is Abby, an attractive senior who is just barely creeping along with enough credits to graduate. She needs his class credits. Abby is told to write a "killer" thesis or Goldman will be forced to explore other options for giving her a passing grade.
Abby's research leads her to Donald Loomis Elementary School where for over thirty years a ghost has been rumored to exist. This legend has been both a source of fear for young students but has also been a beloved mystery of the town since no one has ever been hurt by the creature. They have called it "Chris Knocks" and "Chair Knocker" as its signature is the sudden overturning of chairs when it is around. No one officially believes there is a ghost but they all seem to steer clear of its favorite classroom and no one goes into the school after dark.
Abby is allowed to sit in the abandoned classroom and investigate. This is the room where Chris Knocks prefers to stay in the daytime. According to the legend the ghost only haunts that room in the day but freely wanders the halls at night. The abandoned classroom is cluttered and in disarray with overtunred furinture. The air is stale and gray. It is a room no one likes to go into. Abby sets up in the empty classroom not believing in ghosts herself. It isn't long before Abby actually sees the spector and before she reacts a nearby chair is thrown violently against the wall.
She runs outside and calls Professor Goldman. After some pleading he agrees to come down and investigate himself, prove her wrong, and conclude their passing grade bargaining.
On Goldman's second day at the school he not only sees the ghost in a video image from a camera he had set up but he sees that the ghost is lunging for him. Suddenly Goldman is a believer. They retreat from the classroom for safety and he calls in the help of a professional paranormal investigator. They get permission from the school to stay overnight. They are told the school district secuirty guard will stop by and check on them.
Night comes. They are alone in the dark school. Goldman's research is proving to be confusing - something is wrong. The person he suspects is the ghost was a kind, friendly boy in life, who died tragically at the age of twelve. It doesn't seem like he would become a reclusive and violent ghost known as Chris Knocks.
Something, in fact, is very wrong. There is more than one ghost in the school. The spectral form of the boy is there but there is also a ghost known as Chris Knocks who roams the halls at night. Chris Knocks is very disturbed. Chris Knocks is very dangerous.
Members of the team are attacked and killed as Goldman races to solve the riddle and expel the ghost from our world. But the ghost has other plans.