The tranquil planet of Aritani has suddenly come under attack by a vicious and unknown enemy. The U.S.S. Enterprise rallies to the scene, only to plunge into a deadly nightmare: Spock is found mysteriously injured, his mental powers crippled and weak, and Kirk uncovers an evil Romulan plot -- with a cunning double agent in the middle. As Spock begins to regain his memory, Kirk strives to expose the agent. But only Spock's knowledge can stop the Romulans...from controlling the universe!