After sending a casket bearing Spock's remains to the new greening planet of Genesis, Admiral James T. Kirk returns home aboard the starship Enterprise. Only then does he learn that Vulcan's favorite son has melded his spirit with Dr. McCoy, and they must return to Genesis to retrieve Spock's body and then deliver it to the planet Vulcan. Defying orders to retire their beloved spaceship, our heroes embark on their mission and run into difficulties with the Klingons, a band of outer space pirates who are determined to learn the secret of Genesis.

Trekkies will enjoy this derring-do installment directed by Leonard Nimoy — especially its handling of the mind-body problem and the religious mysticism of the finale.