AllMovie

An unusual astronomical event wreaks havoc with the Enterprise's transporters, and as a result Captain Kirk, Lt. Uhura, Dr. McCoy and Scotty are thrust into an alternate universe. This episode of the original Star Trek series provides a funhouse mirror image of the usual world of the series, as the quartet of officers find themselves in a reality where the Enterprise is a warship for a ruthless, militaristic society that operates by force. Even their fellow crew members have changed, including Spock, who now not only schemes for command and expresses his power over the crew through force, but sports rather sinister-looking facial hair. Kirk and the others must attempt to fit in in this strange universe, without committing any evil deeds themselves, until they can find a way back to their home universe -- and discover what damage their darker selves may have done while there.