Professor Margaret Matheson is a skeptic and expert at debunking bogus paranormal phenomena. Along with her devoted assistant Tom Buckley, she looks into the case of well-known blind psychic Simon Silver. Simon has emerged 30 years after his most persistent critic died under mysterious circumstances. Margaret is determined to identify what she refers to as red lights, the barely discernible characteristics behind each of Simon's planned supernatural events. Starting the case with confidence, Margaret eventually instructs Tom to cease his efforts, afraid of retribution from cunning Simon. Firmly intending to expose Simon as a charlatan, Tom will utilize every instrument within his means to reveal the truth. As his desperate search for what is real grows, Tom is compelled to rethink his own basic beliefs.