is conducting exploratory missions and playing host to Ambassador and Honorary Commander Ari bn Bem, a representative of a recently contacted alien species, the Pandroisans. The ship arrives at Delta Theta III, a newly discovered Class M planet with possible aboriginal inhabitants. Kirk takes down a landing party of himself, Spock, Sulu, and Scotty, to plant monitoring devices. He warns the landing party to beam up immediately at any signs of trouble. They go to the transporter room where Bem is setting the beamdown coordinates. He insists on going with them and Kirk is surprised, noting he's spent the last six missions in his quarters. He warns that the mission could be hazardous but Bem insists on going.
The landing party materializes on the edge of a cliff, and Kirk and Spock are just over the edge. They fall into the water a few feet below and Bem leaps in to assist them. The water is up to their waists, and as he approaches them, the bottom half of his body splits off, approaches the two officers, and substitutes their communicators and phasers for dummies. Bem's bottom half returns as they emerge from the water. Uhura reports that Lt. Arex has detected a sensory anomaly several thousand kilometers west of their position. It doesn't seem to be moving toward them or pose any threat. Spock believes it's a sign of intelligence but Kirk isn't so sure. They proceed into the rain forest and Spock notes that life on the planet seems younger than the age of the star would indicate. Bem picks up a large number of lifesigns ahead of them and then runs into the forest. Kirk and Spock pursue him into the thick underbrush and a seeming dead-end. Unseen by the officers, Bem divides himself into multiple parts and makes his way through the undergrowth. They see him on the other side and make their way around, only to see Bem captured by the local aborigines.
Aboard the Enterprise
, Arex picks up increased activity from the anomaly. Uhura contacts Scotty and orders him and Sulu to beam up to the ship, notifying them she can't contact Kirk and Spock. Meanwhile, Kirk and Spock discover their equipment has been replaced and they can't contact the ship. Kirk insists on going to help Bem regardless and they follow the aborigines to a nearby village. They wait until nightfall and try to rescue Bem. He insists that he allowed himself to be captured so he could observe the aborigines. They open the cage but the aborigines arrive and capture them all.
As they wait, Kirk apologizes to Bem for his inability to rescue them, but Bem notes that good intentions aren't enough and his planetary government will be dissatisfied. The commander isn't impressed with Kirk's ability to perform according to his reputation. Bem reveals he has their equipment and disassembles himself to escape his cage and give them their equipment. Spock realizes Bem is a colony creature and Kirk wonders why he didn't escape. Bem explains that he wanted to see Kirk prove his value to Pandro. Kirk puts him into protective custody and opens the cages using his phaser.
Aboard the Enterprise
, the crew determines that the sensory anomaly has spread to cover the entire planet, cutting off communications. In the aboriginal village, Kirk and Spock try to escape with Bem. The natives spot them but before the landing party can defend itself, a glowing energy field appears and immobilizes them. Kirk introduces himself and explains that they're there to classify the planet. The alien entity takes offense, saying that its "children" are not there for them to test. It destroys the phasers and the aborigines recapture the landing party.
Scotty prepares to send down a landing party armed with phaser rifles. Meanwhile, Bem informs Kirk that he considers him an inadequate commander, and that his people are unconcerned about his personal fate. He notes that Kirk has failed everything he's attempted and then escapes and leaves. Spock suggests they try to contact the alien entity. Kirk tries using his communicator device but it doesn't have enough strength. Spock connects the two in series although he warns it will render them powerless in a short time. Kirk gets through to the alien entity and apologizes, saying he will tell his people not to approach. It approves but doesn't detect a third member and refuses to let them find Bem. Kirk contacts the ship to let them know they're okay, and orders down a security team to scan for Bem. Scotty arrives with the team and frees them and they spread out to find Bem. The aborigines attack and the landing party defends itself with weapons on light stun. They rescue Bem, who apologizes for failing in his judgment.
The alien entity appears, angered that they are still there. Kirk explains that they couldn't leave Bem there to interfere with its children. It agrees. Bem says that he has erred and must disassemble unity. The alien entity intervenes, noting that Bem can't learn from his mistakes if it in essence destroys himself. It does not believe in punishment, and tells them they must leave so that they don't corrupt its children with concepts they're not ready for. Kirk and the others depart and place the planet under quarantine. Bem assures them that Pandro will respect the quarantine. As they leave, Spock notes that the alien entity is practically a god, using the planet as a laboratory. As they break orbit, the alien entity contacts them one last time, saying that they've learned much and have much to be proud of.