The episode “Assignment: Earth” was originally a television pilot for a proposed series about Gary Seven, who, according to “Assignment: Earth”, is a human from the 24th century undertaking a mission on Earth in 1968, “the only Earth man to survive the transit.” His goal in the original series pilot would have been to defeat the Omegans, a race of shape-changing aliens who have sent agents back in time to change Earth’s history so they can defeat Earth in the future.
The pilot was later reworked as an episode for Star Trek, where Seven is now a human raised on a distant planet. The crew of the starship Enterprise, who have been sent back in time by the United Federation of Planets to do detailed research on Earth in 1968, accidentally intercept the transporter beam that is sending Seven to Earth. Seeing humans and Vulcans together, Seven realizes that the starship has come from the future, while the crew suspect that Seven is also a time traveler.
The pilot was debuted as an episode of Star Trek, where Gary Seven, assigned by his planet’s agency as a Class One Supervisor known as Supervisor 194, has been sent to determine why two resident agents, colleagues Agent 201 and Agent 347, had stopped reporting to their superiors. When he discovers that they have been killed in a traffic collision, he takes over their immediate task of sabotaging the launch of an orbital missile platform by the U.S. to prevent nuclear war on Earth.
Seven uses the Enterprise transporter and beams back to Earth into a teleporter that looks like a safe on the outside. The transporter is hidden behind a counter located within his office in Apartment 12B at 811 East 68th Street in New York City. Here, he makes use of his Beta 5 computer, which has a circular view screen and is hidden behind a book case. The computer speaks with a female voice and has broad, though limited, powers. He also shows several high-tech devices he employed such as his servo, the Beta 5 computer and the transporter chamber. The desk also has a blue green cube on it and a typewriter that types whatever is spoken.
His colleagues, Agents 201 and 347, have been using the cover of researching for a new encyclopedia, and hire Roberta Lincoln (Teri Garr) as their secretary. She is originally unaware of Seven’s origins, but as she “possesses high I.Q.”, she realizes swiftly that he is not what he seems; she even guesses that he is alien or from the future. Lincoln tries earlier to foil Seven (thinking him to be a spy), but the two begin to work together.
Seven also has a constant companion in Isis, who at first appears to be an ordinary cat, but is then shown to have intelligence and capability that far exceeds that of an Earthbound feline. Though she gives the appearance of being Seven’s pet, Isis is more. She communicates with him through a rudimentary telepathy and understands his speech. She accompanies him wherever he goes and watches out for him, to the point of being able to find him easily when they are separated. In fact, Isis seems to have a classically magical power, in that she appears able to alter her shape into a different form, or at least create the illusion that she has done so. Lincoln discovers this ability during one of the last scenes in the episode, when Isis appears to her briefly as a human female, wearing a collar similar to the one worn while in cat form, and then reverts into her original feline shape while Lincoln’s back is turned.
At the end of the episode, Spock informs Seven and Lincoln that after a check of Federation records, he finds that the new team has “interesting experiences in store for them.”