Angira is a primitive, violent planet—and young Prince Vikram returns from Earth filled with new ideas. When Sulu and Spock accompany Vikram home, they walk into a bloodbath: reactionary forces, afraid of any modernization, have seized Vikram's rightul throne. Suddenly, the men from the Enterprise are on an underground journey with a prince who is coming of age. The future of Angira is at stake, and each man's survival depends on his skill—and daring—with a sword!