Khan and Kirk duke it out on their respective ships in the Mutara nebula. Khan disables the Enterprise with a lucky shot. Kirk disables the Reliant with an experienced shot. Khan activates the Genesis device only giving the crew of the Enterprise 5 minutes to get out of the nebula. Spock sacrifices his life to jump start the Enterprise and escape the nebula with no time to spare.
Kirk sends Spock's body down to the Genesis planet and McCoy walks off with Spock's katra.