The planet is populated by preindustrial aborigines — the Federation is interested in gathering information about the world for research purposes. While walking through the dense terrain, the crew scans lifeforms emanating from the forest and Bem immediately runs toward them against direct orders. Bem passes through the thick rain forest by splitting into several body parts and floating through the cracks. Kirk and Spock split off but are unable to track Bem through the dense woods. They later discover that he has been captured by a group of angry aborigines.

Scotty and Sulu beam back to the U.S.S. Enterprise and discover a force field developing around the small village, but they cannot contact Kirk or Spock. At night, Kirk and Spock attempt to rescue Bem from the natives but are also captured. Bem explains that he took Starfleet equipment because he dislikes violence and wanted to see how the captain could react without such devices. He returns the devices to Kirk and Spock, who manage escape only to be paralyzed by a supernatural force surrounding the area.

The entity tells them not to interfere with her "children," the people of this world. Bem escapes and Kirk and Spock are again captured. The entity demands that they leave immediately but Kirk tells Spock that they cannot leave without Bem. They arrange a search party to beam down, now that the entity has permitted communications. Bem is found and he realizes that he has failed in his mission and must die. The entity tells him he will not be killed because people must learn from their errors. The crew returns to the ship, where Spock ponders the existence of such a god-like entity and how they are all really children to the universe.