Newly promoted Admiral James T. Kirk (William Shatner) comes face to face with his nemesis, the genetically superior Khan (Ricardo Montalban), who is seeking revenge for having been imprisoned on a desolate planet. A battle ensues over control of the Genesis Device, a top-secret Starfleet project enabling entire planets to be transformed into life-supporting worlds. While Mr. Spock (Leonard Nimoy) mentors the young Vulcan Lt. Saavik (Kirstie Alley), Kirk must battle Khan to the bitter end.