EXCLUSIVE: The Discovery networks have picked up two mystery docuseries after striking a deal with Big Media. Greatest Mysteries Ever and Alien Files: Reopened will air on the Warner Bros.

In April 2011 the FBI declassified decades' worth of secret government documents that contain thousands of reports of UFO sightings and alien activity. Each episode of this half-hour series tackles ...

In the spring of 1952, UFO sightings go off the charts. For years, the U.S. government has told the postwar public that UFOs do not exist, but behind the scenes, U.S. Air Force officials are divided.