Complex sentence: Plasus quickly arrives with a security force, who easily drives the rioting miners off, then invites Kirk and Spock to go with him back to the city immediately while his people search for the zenite.
Split into simpler sentences: Plasus quickly arrives with a security force, who easily drives the rioting miners off. He invites Kirk and Spock to return with him to the city immediately, while his people search for the zenite.