The Enterprise has been on patrol too long - the crew is restless and irritable, especially that Dr. McCoy, the engines are straining, and food is running low. But Captain Kirk is under sealed orders to head to the far away Horatius system to answer a mysterious distress call from some decidedly anti-Federation colonists. When our intrepid crew tries to help, they run afoul of stone-age creeps, drugged fanatics, and oppressed clones. To make matters worse, they face a moral conflict with Federation General Order One, the so-called Prime Directive, which mandates noninterference with native cultures.