The Enterprise returns to dry dock and Kirk (William Shatner) finds Dr. McCoy (DeForest Kelley) acting delirious and talking like Spock. The Starfleet command forbids Enterprise from going back to Genesis, but a research team there led by Kirk’s son, David (Merritt Buttrick) and Saavik (Robin Curtis, taking over for Kirstie Alley) find a life form reading coming from Spock’s coffin. They investigate and find the coffin empty! Meanwhile, we learn from Spock’s father (Mark Leonard) that Spock’s essence has been put into McCoy’s brain, so Kirk defies Starfleet’s orders and takes the crew to Genesis to find Spock’s body.
On Genesis, Saavik and David find a young Spock, who has been reborn from the planet. Before they can be beamed back aboard their ship, it’s blown away by a group of Kilingons led by Krug (Christopher Lloyd) who wants to use the Genesis project as a weapon. Krug beams down to the planet and promptly strangles a giant worm, just because. We learn from David, that he used an illegal “protomatter” to create Genesis, which causes the planet (and Spock) to grow erratically. Spock also goes through aggressive Vulcan puberty and gets the hots for Saavik. (In a scene deleted from part IV, we learn she actually has his baby!)
The Enterprise arrives and battles Krug’s Bird of Prey. The Klingons take Saavik, David and Spock hostage and Krug kills David. On hearing his son is dead Kirk goes into full on Shatner mode: “Klingon bastards! You killed my son!” Kirk goes into action by beaming down to the planet and takes out a bunch of Klingon’s by blowing up the Enterprise! Kirk finds Saavik and Spock and fights Krug to the death (guess who wins). They hijack the Bird of Prey and high tail it to Vulcan to merge Spock’s essence with his body. The Spock we all know and love finally shows up and remembers Kirk. The End.
It’s pretty entertaining, but not up two part 2’s high standards. David’s death pales in comparison to Spock’s sacrifice in Wrath of Khan. Spock, such an integral part of the chemistry of the characters is sorely missed throughout. Nimoy’s direction is fast paced, but it would take another go round in the director’s chair for him to fully hit his stride. McCoy gets the most laughs in this one, especially the scene in the bar when he tries to put the Vulcan neck pinch on someone. Also with Nichelle Nichols, James Doohan, George Takei, Walter Koenig, some Tribbles, and Miguel Ferrer in a bit part.