To escape his desk job, Adm. James T. Kirk (William Shatner) returns to the USS Enterprise, assisting Spock (Leonard Nimoy) in a training mission for Starfleet cadets. But the inexperienced crew is put to the test when escaped villain Khan (Ricardo Montalban) steals a powerful weapon and comes after the admiral seeking revenge. Now, Kirk must use all his wiles and whip the cadets into shape if they hope to defeat Khan's deadly traps.