Guest stars:

Robert Lansing          Gary Seven, 20th C human raised on another secret planet from ancestors taken from earth long ago. supervisor 194 to aide in survival of earth

Terri Garr              Roberta Lincoln, youthful human
Jim Keefer              Cromwell
Morgan Jones            Nesvig
Lincoln Demyan          Rawlings

Crew appearances:
Kirk, Spock, McCoy
Uhura
Sulu
Chekov
Scott (also voice of mission control)
Voice of Bela 5 computer:  Majel Barrett
 
In this pilot for a separate series, the Enterprise is doing some Earth research of social crisis in the 20th Century, when they intercept Gary Seven's transporter beaming to earth. He is a human who had been captured by alien beings from an unknown and secret planet 1000 L. Y. away, and trained to save mankind from destroying itself. Seven teams up with secretary Roberta Lincoln and tries to carry out his assignment. Kirk's dilemma is that he isn't sure of Seven's true intentions: will he help mankind or destroy it?  Seven's assignment is to destroy a rocket with a nuclear warhead that will start WWIII if left alone without intervention by Seven.

Light speed breakaway factor: used to hurl the enterprise into 1968. Not shown but talked about

Omecron 4: mentioned to have had a similar crisis with balance of power that almost distroyed the planet

Spock's neck pinch doesnt work on Gary 7.

Quotes:
"Well, how do you expect me to type, with my nose?"  Roberta.