Kirk steals the Enterprise to recover Spock's katra from the Genesis planet.
Star Trek III: The Search for Spock, released in 1984, was directed by Leonard Nimoy and continues directly from the previous film. After Spock's death, Kirk and the crew return to Earth, only to learn that Spock's spirit, or katra, has been placed in Dr. McCoy, who is now troubled by it. Meanwhile, the Genesis planet is being studied, and rumors suggest that Spock's body may still be there.
Kirk makes a daring choice and, with his friends, steals the Enterprise from Spacedock in defiance of Starfleet orders, in order to restore both McCoy and Spock. The mission is complicated by a Klingon commander named Kruge, who wants the Genesis technology as a weapon. The story weighs loyalty against duty and the price of friendship, and it asks what it costs to save someone you love.
The film is the middle piece of a three-film arc and one of the more personal stories in the series. It sees the loss of the Enterprise, a heavy blow for Kirk, and a ceremony on Vulcan that restores Spock. It shows the loyalty of the crew and sets the stage for the next story.