Stardate not given: The Enterprise is sent on a mission back to Earth in the year 1968 to discover details about how the planet survived the arms race. While in orbit, the ship intercepts a transporter beam from an unknown part of the galaxy and beams the space traveler aboard. Surprised by what has taken place, the man identifies himself as Gary Seven and claims to be a 20th Century Earthman raised on an unknown world and trained to prevent Earth from destroying itself. Kirk decides to verify Seven's story before releasing him, but Seven escapes and beams down to the planet below. Kirk and Spock follow him to New York City, and Seven meanwhile discovers that two of his fellow agents have been killed in a auto accident. Seven is forced to complete their mission himself which is to sabotage an orbital nuclear platform, just low enough in the atmosphere to scare Earth leaders into prohibiting additional nuclear space weapons. Just as Kirk and Spock arrive, Seven beams out of his office a
Elenco: William Shatner , Leonard Nimoy , DeForest Kelley , Majel Barrett , Walter Koenig , George Takei , Nichelle Nichols , James Doohan , Majel Barrett , Bill Blackburn , Frank da Vinci .