The planet Sanctuary -- a fabled world in unexplored space which is thought to be the last refuge of the persecuted, home to both the justly and unjustly accused. Though its name has been translated into every language in the galaxy, Starfleet has never known its exact location. When the crew of the USS Enterprise is assigned to capture a dangerous criminal named Auk Rex, their pursuit takes them to an unexplored sector of the space. Captain Kirk, Mr. Spock, and Dr. McCoy continue the pursuit in a shuttlecraft, following Auk Rex to the surface of the planet, Sanctuary. Soon, Kirk and his crew are locked in a life and death stuggle on the mysterious planet, which harbors deadly secrets and never releases its visitors.