Retired and happily married, Kirk believes his adventuring days are over. But as he returns to Earth for the first time since his apparent death upon the Enterprise-B, events elsewhere in the galaxy set in motion a mystery that may provide Kirk with his greatest challenge yet.

James T. Kirk returns to the mirror universe that was first seen in the original televised Star Trek, to engage in a battle with the cleverest and most dangerous foe he has ever encountered, his mirror universe duplicate.

Captain Kirk is helpless to prevent his evil twin from capturing him, but the reappearance of the long-dormant "Preservers" will threaten the entire galaxy, unless he can prevent them. Reprint.