Executive producer: Gene Roddenberry
Associate producers: Edward K. Milkis and Gregg Peters
Producer Fred Freiberger
Co-producer: Robert H. Justman
Story consultant: Arthur H. Singer

Story by Michael Richards (D. C. Fontana) and Arthur Heinemann
Writer: Arthur Heinemann
Dir.: David Alexander

Captain Kirk: William Shatner
Science Officer, First Officer, Cmdr. Spock: Leonard Nimoy
Dr. Leonard "Bones" Mc Coy: DeForest Kelly
Lt. Sulu: George Takei
Lieutenant Commander Montgomery Scott: James Doohan
Lieutenant Uhura: Nichelle Nichols
Dr. Sevrin: Skip Homeier
Irini Galliulin: Mary-Linda Rapelye
Adam: Charles Napier
Tongo Rad: Victor Brandt

Stardate 5832.3

The Aurora is a stolen space ship and it is right in front of the Enterprise. They pursue the ship after no call was answered. Trying to escape, the Aurora speeds up and overheats it's engines. Just before it explodes, Kirk orders the people on board to be beamed onto the Enterprise. A group of people, under the lead of Dr. Sevrin, materializes. All object rules and authority, but value independence and freedom. They reject hate and hate the Federation. Interesting individual outfits underline their attitudes. Kirk's offer to host them as guests instead as prisoners is met with laughter – ignoring the fact that they have stolen a ship and the crew has saved their lives. 

No communication seems possible when Spock suddenly offers to try himself. He stands in front of the group and asks: "Do you know this sign?" while he forms a triangle with both hands. The leader stands up and answers, showing the same sign. "we are one". A relieved Kirk orders Spock to care for the group. Because of exposure to rays, Kirk orders all to be medically examined. All refuse. One by one they are "helped" by medical assistants into the examination rooms where McCoy checks on their health. Dr. Sevrin is the last to go. With him McCoy discovers synthococcus novae, a disease of which he is a carrier but the illness did not break out. By being a carrier he jeopardizes the others. Of course he is aware of it and he admits it to to Mr. Spock, to whom the group has an "antenna". But he does not want to live in isolation. The others want to find the planet Eden, and this is the place he longs for, too. 

Spock is visited by Adam, one of the group who always finds a way out of difficult situation by playing a kind of electric guitar. In Spock's rooms Adam finds an instrument and asks Spock to play it for him. Spock agrees and Adam suggests a jam session at the Enterprise playing music to all. Having Spock's consent he rushes to the others to tell them that their plan will work out: To take over the Enterprise. In addition to that Irini, who was acquainted with Chekow some years ago, convinces Chekow that it would be interesting for the group to have a look at the machine room. Sevrin is accommodated in a room which separates him from the other for their own protection. 

Meanwhile Spock has found out about planet Eden: It really exists and he has got the coordinates. And the session begins. The group sings and performs with instruments entertaining the crew. Spock joins in playing the Vulcan harp. Too late the crew finds out that the session was a trap to give the group time to take over the engine room and lock themselves in efficiently. One has "freed" Sevrin for they never believed in the illness Spock had informed them about. Steering the ship towards Eden they succeed in maintaining the course. The ship is spread with ultrasonic sounds which render the crew members unconscious and nearly kills them. 

Having reached the planet Eden the groups steals a shuttle craft and heads for the planet. Spock, Kirk, McCoy and Lt. Chekow after them. First Chekow burns himself – he had tried to touch a plant in this paradise like looking environment. Then Spock finds Adam. He is dead. He tried to eat a fruit from a tree. They find the others – feet burned because they tried to walk on the sand (and all disillusioned)- in the shuttle. They carry them away. Only Sevrin, who knows that he is bound to die, pushes them away and climbs a tree in spite of his burned feet. He eats a fruit knowing he will die. And he does. McCoy and Spock come too late – he has bitten into the fruit and swallowed it to die with his dreams which have died here. Leaving the toxic planet the rest of the group needs to get new orientation for new aims. Spock wishes Irini the best: He believes she will find her paradise or she will make one for herself.