Newly declassified documents could link the Roswell crash to Nazi science, fresh evidence may reveal what's really hidden inside Area 51 and experts investigate the dark secrets of the Dugway Proving Ground.

Experts investigate disturbing phenomena at Skinwalker Ranch, top-secret experiments may have been conducted at a former Air Force base in Long Island, New York, and new theories could explain why Mount Shasta is a magnet for paranormal activity.