An alien female beams aboard the ship and, after incapacitating the rest of the crew, surgically removes Spock's brain. Kirk and the crew have just hours to locate and replace it before Spock's body dies.
Quest roles:
Majel Barrett(Nurse Christine Chapel / Enterprise Computer (voice)), Frank da Vinci(Lt. Clifford Brent), Marj Dusay(Kara), Sheila Leighton(Luma)