Admiral Kirks defeat of Khan and the creation of the Genesis planet are empty victories.

Spock is dead and McCoy is inexplicably being driven insane.

Then a surprise visit from Sarek, Spocks father, provides a startling revelation: McCoy is harbouring Spocks living essence.

With one friend alive and one not, but both in pain, Kirk attempts to help his friends by stealing the U. S. S. ENTERPRISE and defying Starfleets Genesis planet quarantine.

But the Klingons have also learned of Genesis and race to meet Kirk in a deadly rendezvous.