The dark crystal

A thousand years ago on the planet Thra, two new races appeared when a Shard was shattered from the Crystal of Truth: the cruel Skeksis, who use continued corruption of the Crystal to extend their lives, and the gentle urRu, more commonly known as Mystics, who make their home in the Valley of Stones to await their destiny. The leader of the Mystics, the Master UrSu, raises a young Gelfling named Jen whose clan were slaughtered by the Skeksis. As the Great Conjunction of Thra's three suns draws near, a dying UrSu instructs Jen to fulfil a prophecy to heal the Crystal by first retrieving the Shard from Aughra. If Jen fails to complete his quest before the three suns meet, the Skeksis will rule forever.