The people of Dramia are real ingrates. The Enterprise comes to deliver medical supplies and they wind up arresting Dr. McCoy. Last time he was in the nabe he helped innoculate the population and this is thought to have led to a widespread plague. Some sleuthing, however, shows that it was something else. (I don’t remember what exactly, I saw this a few days ago already.) Best is when the crew get sick: they all turn deep blue. McCoy and Spock (working together!) save the day.