Jacqueline Gets Sent to the Star Wars Universe

After losing contact with the planet Deneva (population 1 million) for more than a year, the Enterprise goes to investigate. Uhura's attempts to make contact at all frequencies, including private GSK783 subspace frequency 3, but without success. Spock consults the computer and discovers that waves of mass insanity have swept along a straight path through planetary systems Beta Portalin, Lavinius 5 (200 years ago), Theta Cygni 12, and Ingrahem B (2 years ago). Deneva (colonized a century ago and one of the most beautiful planets in the area) is the next planet on this path, and Kirk expects the worst for his brother Sam and his family.
While approaching the planet, the Enterprise encounters a Denevan ship heading straight for the sun. Attempts to convince the pilot to change course fail, and the pilot flies into the sun. Just before being vaporized, the pilot makes the cryptic statement "I did it. It's finally gone," and claims that he is finally "free." Uhura finally gets through to the private transmitter, and hears the message "Please hurry, help us, I don't have much time. They'll know," being transmitted by Sam's wife Aurelan.
When Kirk beams down with a landing party, a group of armed men attempts to attack them with clubs, while at the same time shouting that they don't want to hurt them. Responding to a scream, the landing party finds Sam (who was a research biologist) dead and his wife Aurelan and son Peter in great pain. Aurelan refers to invaders, but the tricorder shows nothing unusual. After Aurelan and Peter have been beamed to the Enterprise and questioned as far as they can be, Aurelan reports that the invaders came from planet Ingraham B eight months ago after forcing the crew to take them there. She reports that the invaders use pain to control people and are forcing the residents of Deneva to build ships for them.
Kirk, Spock, and a landing party enter a building in which they find hundreds of small creatures which look like plastic pancakes. The creatures do not register on the tricorder and are highly resistant to phaser fire. When leaving, one of the creature whirls towards them and attaches itself to Spock's back. Back on the Enterprise, McCoy finds that Spock's nerves are being surrounded with strange tissue. Despite his incredible pain (as shown by the K3 indicator), Spock escapes from the sickbay and attempts to take over the bridge before being subdued and tranquillized. While trying to subdue Spock, Jacqueline is sent into the Star Wars universe. She lands onto a planet, unconscious.
Three Imperial stormtroopers find the unconscious Jacqueline and bring her back to the Super Star Destroyer Executor. When Jacqueline regains consciousness, she finds that she is in her counterpart's clothes. Jacqueline is greeted by Darth Vader. Vader says "Greetings, Queen Jacqueline!" Jacqueline says "Greetings, Lord Vader!" Vader says "I am relieved to see that you are all right, your Majesty!" In the Star Wars universe, Jacqueline was the Queen of the Galactic Empire. She ruled the Galactic Empire alongside Emperor Palpatine, the ruler of the Galactic Empire. Darth Vader then turns to one of his admirals. He says "Admiral, you were supposed to protect the Queen!" The admiral says "But, Lord Vader--!" Vader says "Your carelessness cannot be tolerated! You have failed me for the last time, Admiral!" Darth Vader then uses the Force to choke the Admiral to death.
Immediately, Jacqueline guesses that her mirror universe counterpart is on the USS Enterprise! Jacqueline must impersonate her counterpart until she can find a way to return to her own universe!
Aboard the USS Enterprise, Captain Kirk recognizes the mirror Jacqueline and orders security to take her to the brig.
Back on the Executor, Jacqueline goes to her quarters and finds it very different from her own. Jacqueline realizes that she and the Empire have been ordered to destroy the Sakorans! Horrified, Jacqueline uses the computer and discovers that her counterpart became the queen of the Galactic Empire when Palpatine declared himself Emperor and started the Galactic Empire and that she was responsible for the massacre of 5,000 Imperial colonists on Kalkus II, among other atrocities.
Darth Vader tells Jacqueline that the Executor is ready to attack the Sakorans! Desperately, Jacqueline orders a delay in the attack for 12 hours! This piques Vader's curiosity, but he obeys the order! Vader reports the suspicious activity of the Queen to his Master, Emperor Palpatine! The Emperor orders Vader to kill Queen Jacqueline if she does not carry out her orders by destroying the uncooperative Sakorans!
Jacqueline meets up with her best friend, Gina. Gina came to the Star Wars universe looking for Jacqueline. Jacqueline tells Gina to find a way to return her to her own universe. While Gina finds a way to return Jacqueline to her own universe, Jacqueline meets the mirror-Laura. The mirror-Laura shows Jacqueline the Vakarius Device, a device that she recovered from an alien civilization. Jacqueline has been using the Vakarius Device to eliminate the Emperor's enemies. When Jacqueline stops the mirror-Laura from eliminating Darth Vader, mirror-Laura realizes that something is wrong--the Queen would not have hesitated.
Jacqueline continues to stall for time while Gina finds a way to return Jacqueline to her own universe, but Vader is suspicious. Darth Vader decides to study Jacqueline for as long as he can.
Gina reports to Jacqueline that she found a way to return Jacqueline to her own universe. Then Darth Vader confronts Jacqueline and takes her to sickbay. In the ensuing fight, Jacqueline knocks Vader unconscious. Gina stays behind to make sure that Vader is all right while Jacqueline rushes to the transporter room. Vader regains consciousness and mind-melds with Gina. Vader discovers that a switch has occurred. Darth Vader decides to help Jacqueline return to her own universe. Darth Vader volunteers to operate the transporter. Jacqueline tells Vader that he still has good in him. Jacqueline tells Vader that, in the future, he will kill Emperor Palpatine and save his son, Luke Skywalker! Darth Vader says "When the time comes, Jacqueline, I will kill the Emperor! You have my promise!"
Aboard the USS Enterprise, Captain Kirk decides to attempt the beaming sequence the same as the Executor attempts theirs. The exchange is successful. Jacqueline is beamed back aboard the USS Enterprise with Gina.
When Jacqueline returns, Captain Kirk tells her that the Denevan neural parasites have been destroyed. He also tells her that Spock had been blinded by the extreme light that freed him from the creature. Spock had regained his sight after the Denevan neutral parasites had been killed. Jacqueline also introduces Captain Kirk to Gina.
Back on the bridge, Jacqueline meets her own universe's Laura, who is quite a different girl from what she experienced her to be in the other universe. Jacqueline tells Captain Kirk that Laura has been her friend for a long time. Captain Kirk also tells Jacqueline that the ruthless attitude of the mirror Jacqueline was very refreshing and the very flower of humanity!