The Enterprise crew arrives at a planet a hundred years after another ship arrived there. The Iotians are an imitative race and have patterned their culture after the 1920's gangster culture of the U. S. This happened because someone left a book on he planet outlining the gangland characters. This has become their Bible. There is a battle going on for territory as the factions put hits on each other. The joy of the episode is watching Kirk and Spock try to adapt to the society without encroaching on he prime directive. There are great scenes as Kirk, and even more ridiculously, Spock try to mimic the dialect and nomenclature of the time. There is the priceless scene the two attempting to drive a flivver. Kirk jerks along, not quite getting the hang of the clutch, and Spock tells him he is a great captain but a horrible, dangerous driver. The guys need to meet the gang bosses on their own level, but what is this. Anyway, it is great fun and one of the most memorable in the series. One other thing, Kirk and Spock look great in those zoot suits.