has used the slingshot effect (from "Tomorrow is Yesterday") to travel back in time to Earth, circa 1968, for the purposes of historical research. However, the ship is shaken when it suddenly intercepts an incredibly powerful transporter beam focused toward Earth. Spock and Scotty struggle to adapt the ship's transporter system to receive the alien teleport beam before it rips them apart. Successful, the passenger materializes: a human wearing a 20th century business suit and holding a black cat.
Why have you intercepted me?
The newcomer is nonplussed by his strange environment. As Kirk arrives with a security team, the man recognizes Spock as a Vulcan and realizes they're from the future. He identifies himself as Gary Seven and insists they beam him down to Earth. He explains he was taken by an alien planet that has Earth's interests at heart, trained as an operative, and sent back to aid the planet. The aliens have hidden themselves from sensors, even in the future. Spock warns that as Seven is a human native to the time zone, if they fail to beam him down they could be altering history. Kirk decides against beaming Seven back down and the man attacks the assembled group and tries to take control of the transporter. He overpowers the four humans and is resistant to Spock's nerve touch. Finally Kirk stuns him with a phaser, then orders him to the brig while McCoy does a thorough medical exam.
You interfere with me with what I have to do there, and you'll change history. You'll destroy the Earth ...
and probably yourselves, too.
Kirk calls a shipwide briefing from the conference while Spock considers the cat, Isis. However, neither Chekov nor Scotty have anything to add: an analysis of the teleport beam reveals nothing. Spock notes that there are three significant historical events happening in that date, the most significant of which is the launch of an American nuclear weapons platform. However, that doesn't give any indication to Seven's objectives. McCoy notes that Seven is human, but perfectly so. Meanwhile, Seven uses a pen-servo to disrupt the force field in the brig and stun the guard, then makes his way to the transporter room. Isis leaves the conference room and joins him. As they prepare to beam down while scrambling the coordinates automatically after departure, they set off a security alert, but Kirk and the others arrive there too late as Seven dematerializes with his cat.
You're tired, go to sleep.
Seven and Isis complete their aborted journey and arrive at a hidden chamber in an apartment in New York City. The two expected operatives aren't present and Seven speaks with the Beta 5 computer, which forces him to establish his credentials by stating his mission: to ensure that Earth isn't destroyed. Meanwhile, on the enterprise
Scotty manages to narrow down the area where Seven beamed down to, but someone will have to go down to pinpoint the location further. Kirk and Spock, familiar with time travel, go down alone to minimize the chance of altering history.
Computer, I caution you. I have little love for Beta-5 snobbery.
The Beta 5 computer explains that Seven's two fellow operatives were going to sabotage the rocket bearing the nuclear platform but have lost contact three days ago. The rocket will launch in just over an hour. Meanwhile, Kirk and Spock close in, dressed as natives. They're unaware that a young secretary, Roberta Lincoln, is entering the building. She goes to Seven's office where he mistakes her for the missing female operative. He tells her to make a report using a futuristic voice-activated typewriter, which freaks her out. He has the computer scan her and determine she's a native who thinks she was working for encyclopedia researchers. Seven shows him fake papers identifying himself as a CIA agent and convinces her to stay so she doesn't give any secrets away. He then has her man the desk while he goes into his office.
Roberta Lincoln. Human. Profession--secretary. Employed by 347 and 201.
Description -- age 20, 5'7",
120 pounds. Hair presently tinted honey blonde. Although behavior appears erratic, possesses high I.Q.
- Birthmarks… small mole on left shoulder. Somewhat larger star-shaped mark on her…
Hey, watch it!
Kirk and Spock pinpoint Seven's location while inside, the Beta 5 determines that the two operatives died driving to McKinley Rocket Base, where the rocket is launching. Roberta lets Kirk and Spock in but when they try to get through to the office, she struggles with them, inadvertently pulling off Spock's concealing hat. She manages to call the police while Kirk gets into the office only to find that Seven has disappeared, having used the hidden teleporter. Kirk finds a map of McKinley Rocket Base as the police arrive, and he calls for beam up. Kirk, Spock and the two policemen end up on the Enterprise
, where Kirk quickly beams them back down again before they can do anything but stare in shock.
What are you?
Seven arrives at McKinley where a security guard spots him and asks for his papers. Despite the fact he has a forged set of NSA papers, the guard prepares to call in to security. Isis distracts the sergeant long enough for Seven to stun him and then hide in the flight officer's car. Meanwhile, Scotty tries to locate Seven by bouncing signals off of a weather satellite. The flight officer drives to the gantry for final inspection and Seven sneaks out and goes up the elevator with Isis.
There's an old-style weather satellite in orbit below us. If I could bounce off it, I could get some good views.
Spock and Kirk beam down in civilian disguises but the sergeant wakes up and arrests them. In New York, Roberta is fiddling with Seven's desk and opens the hidden teleport vault. With twenty minutes left to launch, Seven starts sabotaging the rocket. The flight officers try to figure out what Kirk and Spock's equipment is, while Scotty spots Seven and starts beaming him up. However, Roberta activates the teleport controls at the same time and yanks Seven out of the transport beam and back to his New York office.
"Meow"? You are nervous, aren't you, doll?
Kirk and Spock can only look on as the rocket launches as planned. Seven tries to take control of the rocket via his alien computer, but it's clear by now that he's up to something and Roberta tries to call the authorities. Seven severs the phone cord and locks her in, then arms the rocket's nuclear warhead and takes it off course. McKinley launch control realize something is wrong but there's nothing they can do. Scotty risks calling Kirk and the sergeant picks up the communicator. Spock renders him unconscious and Kirk signals to be beamed to Seven's apartment.
Are you jealous, Isis? Most unbecoming?
Roberta knocks out the distracted Seven with a metal cigar box and takes his pen servo. He recovers enough to try and explain that he's on her side but she doesn't believe him. Kirk and Spock arrive but Spock is unable to master the computer controls and Roberta won't let Seven intervene. She is suspicious of Kirk as well and threatens him with the pen-servo, and Seven grabs it for her: it's accidentally set to kill. Kirk is forced to trust him and lets Seven go to the controls. Seven detonates the warhead just before it enters Earth's atmosphere. Making his report, he notes that the scare has frightened the world powers into cutting back on the arms race. Spock notes that everything went exactly as their history tapes show, while Roberta notices that Isis has briefly transformed into a woman. Seven pretends not to know what she's talking about and Isis has transformed back by the time everyone else looks. Kirk and Spock leave, but not before noting that their historical records show that Seven and Roberta have a number of interesting adventures ahead of them.
Would you mind telling me who that is?
That, Miss Lincoln, is simply my cat.