From the Back Cover
The Enterprise and her crew become lost in space when a test on the ship's propulsion system backfires and blasts the starship more than a billion light years from its own galaxy.
The arrogant Starfleet propulsion expert is held accountable for this disaster until Wesley Crusher (Will Wheaton) reveals a meek, humanoid alien called "The Traveler" to be the true catalyst...and the Enterprise’s only hope for survival.
But the alien is weak and dying, and in this galaxy physical and mental worlds are integrated-what the crew thinks becomes real. Now the crew must fight to control thoughts and keep the alien alive...before time runs out.
This is one of my altime favorites from season 1. I love special effects and this has someof the best.