A young woman is brought aboard the "U.S.S. Enterprise" by Lt. Reilly's contact team, unaware that any world exists outside her own spaceship. With her craft plagued by mutiny, Kirk and company must gain control of the ship before it, and their disoriented passenger's identity, are destroyed. They also need to convince the woman that their purpose is not part of a malefic scheme, as she fears. The crew also realizes that it would be better to sway her feelings before she gets a good look at Spock!