Ever been told "it's all in your head"? Just how true is that statement? This provocative "Nova" documentary explores four puzzling case studies involving the mysteries of brain science. Join pioneering scientist V.S. Ramachandran as he investigates one person's phantom limb pain, another's messianic identity crisis, a young man's certainty his parents are impostors, and the baffling conundrum of a blind man with the power of vision.