"Mirror, Mirror" was an episode of the original series of Star Trek: The Original Series. It is a second season episode, #39, and was broadcast for the first time on June 10, 1967. It was written by Jerome Bixby and directed by Marc Daniels .

The episode introduces the alternate reality "Mirror Universe" concept in Star Trek for the first time. The stardate of the episode was never revealed.

After failing to persuade the Halkan Council to allow the Federation to mine dilithium crystals on their planet, Captain Kirk, along with Dr. McCoy, Scotty, and Lt. Uhura, return back to the Enterprise. The effects of an ion storm however, create a mishap during transport, and the landing team beams aboard an unfamiliar Enterprise.

The team discover they have entered a parallel universe to their own, where the U.S.S. Enterprise is called an Imperial Starship or I.S.S. Enterprise, and the Federation is now called the Terran Empire. The group's uniforms have also changed into more "revealing" outfits, including a decorative sash tied about their waists. Uhura now bares her torso, while the men's uniforms are sleeveless tunics. Kirk also notices he now has a set of strange medals on his chest.

The group's first experience in this hellish reality is the unforgiving torture of the transporter operator by Mr. Spock who now sports a menacing looking goatee, and a device called an agonizer. Mr. Spock administers the punishment for almost losing the Captain to the operator's carelessness. Almost immediately, Kirk guesses that the "other" landing party must have beamed aboard his Enterprise but the crew here doesn't know this. The team decides to impersonate their mirror image counterparts for now, until they find a way to return to their universe.

Back on the U.S.S. Enterprise Mr. Spock discovers the persona of his Captain and the rest of the landing party has changed significantly. Almost immediately, the anti-Kirk questions Spock about his missing beard and why everything has changed. Suspecting some kind of conspiracy, the anti-Kirk goes on a rampage and Spock orders security to take the landing team to a holding cell. The anti-Kirk tries to bribe Spock with rewards of "his own command" if he's freed. Spock simply replies "fascinating" and goes about his investigation into what has happened. Spock determines that the ion storm must have opened a barrier between parallel universes, and somehow, the landing team's counterparts switched places.

Back on the I.S.S. Enterprise Kirk goes to his quarters, which is very different that he's used to, and examines his mission orders. He learns that he has been ordered to annihilate the Halkans if they refuse the Empire's "request" to mine dilithium. Horrified, Kirk studies his counterpart's records further, learning he succeeded command of the I.S.S. Enterprise by assassinating Captain Christopher Pike, and that he also was responsible for mass murdering 5000 colonists on Vega IX .

Anti-Spock informs Kirk that the ship is ready to attack the Halkans, however Kirk orders a delay in the attack for 12 hours. This piques Spock's curiosity, but he obeys the order. Kirk then survives an assassination attempt by Mr. Chekov, and Spock subjects Chekov to an agony booth and tortures him. Kirk finds out the fastest way to promotion around here is to kill your superior.

Meanwhile, Scotty and McCoy work secretly to figure out what happened with the transporter. While Scotty is finding a way to return them back to the correct universe, Kirk meets the beautiful Lt. Marlena Moreau , who refers to herself as the "Captain's Woman." At the same time, anti-Spock reports the suspicious activity of his Captain to the Imperial Command, and receives orders to kill Captain Kirk if he does not carry out the order to destroy the resisting Halkans.

Back in Kirk's quarters, Marlena discovers her Captain has changed, and Kirk tells her he is from a different universe and must find a way back to his. She shows Kirk the Tantalus Field, a device which can secretly monitor anyone on the ship and "eliminate" them at his leisure. During a second assassination attempt, this time by Lt. Sulu, Marlena kills Sulu's conspirators with the device.

Kirk continues to stall Spock until his team can find a way back to their reality, however Spock, not wanting command of the Enterprise, as it would make him an instant target of assassination, decides instead to study the Captain as long as he can. Marlena wants her Kirk back as well, and helps the team return as much as she can.

Scotty reports to Kirk that he may have finally found a way back. Still thinking anti-Spock will be a problem, Kirk knocks him unconscious, and Uhura, Kirk, and Scotty head for the transporter room while McCoy stays behind to make sure that anti-Spock is all right. Spock suddenly comes to and quickly mind melds with McCoy. He discovers that the switch had occurred, but anti-Spock surprisingly agrees to assist Kirk in returning his landing party to their own universe. This gesture confers in Kirk that this Mr. Spock is still an honest and cooperative person despite the current environment. He suggests to anti-Spock a revolution, that a Federation-like system is better than the ruthless totalitarianism of the Empire. Anti-Spock seems to curiously agree.

Meanwhile on board the U.S.S. Enterprise, Spock decides to attempt the beaming sequence at the same time the I.S.S Enterprise attempts theirs. He has the anti-landing party take their positions on the transporter pads and prepares to beam them out. The transport begins at the same time the Imperials beam their party out. The switch back occurs successful, and the landing party is repulsed when they learn about their counterpart's barbaric personalities.

Later, back on the bridge, Kirk meets Lt. Marlena Moreau, who is quite a different girl than what he experienced her to be in the other universe.

Trivia

The episode is followed up in Star Trek: Deep Space Nine episodes, starting with "Crossover ".

The Mirror Universe is also traveled to by the Star Trek: The Next Generation crew in the novel Dark Mirror by author Diane Duane.

The Mirror Universe Spock's goatee, has since become a part of popular culture and the namesake of the band Spock's Beard.

External link

• Mirror, Mirror at Memory Alpha, a Star Trek WikiWiki