A 9/11 survivor, an astronaut and a blue hole diver - all survived dramatically different traumatic events only to tell strikingly similar stories: each felt a mysterious presence that guided them to safety in their time of greatest peril. But what were these strange presences? Can they be explained? The devout call them guardian angels or divine encounters - others encounter a kind stranger. Could they have been angels? Phantoms? Or were their minds just playing tricks on them? EXPLORER delves deep inside this phenomenon to break down the barrier between science and the supernatural. When faced with life and death, the brain flips an "angel switch," and help arrives-at least for some. Dubbed the "Third Man Factor," hundreds have reported this mysterious phenomenon - and now, science is taking a closer look, zeroing in on the location and the mechanism in the brain they believe may be responsible for these visions.