While searching for the crew of a destroyed spaceship, the Enterprise discovers a planet whose oppressive government is a 20th-century version of Earth's Roman Empire. Kirk, Spock and McCoy meet the rebels, seemingly sun worshipers, but are soon thereafter apprehended by the regime. The missing Captain Merik is revealed as the “First Citizen“ and a pawn of the regime, but he and the rebels ultimately help Kirk and company to escape. Back on the Enterprise, Uhura observes that the crew's understanding of the rebels as sun worshipers was not completely accurate.