Rev. Bob Larson has performed more than 10,000 exorcisms over a period of 30 years. In this one hour interview, he explains how a demon invades a person and why. He discusses his 10 Rules for Exorcising a Demon and shows how an exorcism is like a chess game, with many calculated moves. He also demonstrates how to delineate between a person invaded by a demon and someone suffering from a mental illness.