Saavik does appear in the film, but actor Robin Curtis replaced Alley. Curtis went on to reprise the role in the next "Star Trek" film, but the recast was jarring to fans.
In Leonard Nimoy's book "I Am Spock," he wrote that Paramount "dropped the ball" on Alley's first contract. There should've been a clause for a sequel with predetermined pay.
"We contacted her while the script was still in the works, and the salary we discussed was reasonable," Nimoy wrote. After realizing how large of a role it was, Alley renegotiated.
"We couldn't agree to the price on either budgetary or ethical grounds, but Kirstie and her agent held firm," Nimoy wrote. "We had no choice but to search for a new Saavik.'"