Executive Producer: Gene Roddenberry
Producers: Gene L. Coon + John Meredyth Lucas
Associate Producer: Robert H. Justman
Script Consultant: D. C. Fontana

Writers: Stephen Kandel + David Gerrold
Dir.: Marc Daniels

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
Nurse Christine Chapel: Majel Barrett

Harry (Harcourt Fenton) Mudd: Roger C. Carmel
Stella Mudd: Kay Elliot
Norman: Richard Tatro
Alices: Alyce and Rhea Andrece
Hermans: Tom and Ted LaGarde
Barbaras: Collen and Maureen Thornton
Maisies: Tamara and Starr Wilson
Lt. Rowe: Mike Rowden
Ensign Jordan: Michael Zaslow

Stardate: 4513.3

Dr. McCoy shares with Spock his worries about crewman Norman, after they have passed him in the corridor: Norman seems different to McCoy, he never talks about his past, McCoy says and indicates that this is strange. Spock does not find it strange at all and tells McCoy it is much too early to evaluate a new crewmember after such a short time of service –72 hours. Norman brakes into the second control room and changes course of the Enterprise. In the engine room Norman beats down everybody and makes sure the ship maintains his changed course. Norman tells the crew on the bridge taht he has taken control of the matter-antimatter system and would be able to make the ship explode and demands to take over the ship. Spock checks his controls: "He's a robot, captain." 

Norman names the people who are to be beamed down when they reach the planet he had set course for: Captain Kirk, Mr. Spock, Mrs. Uhura and Mr. Chekov. Down at the planet they meet Harry Mudd again, who introduces himself as Mudd I, ruler of the planet. He is surrounded by beautiful women. When one of the women smashes Kirk's communicator with one hand and Kirk gets angry at Mudd, who in turn enjoys his power and invites them to stay and relax. Mudd shows them "model Alice" several times and says he's made himself 500 of them. "500 of the same model?" Spock wonders, "I find this somehow boring."

When Kirk refers to the incidents on Rigel IV, Mudd denies of having stolen anything. When Spock says he's never paid, he agrees- he had never promised anything and kept that promise. After stealing a ship and being shot at, so that he could not maneuver it, he came to this planet and found several hundred robots there. They gave him the ruling position in return for his connections to bring in new humans they could copy. Now he wants them to take over so that he can go on to other planets. 

He has made a copy of his wife, Stella Mudd, who always scolded at him – to silence her whenever he wants. They are led to their rooms and Kirk asks Norman about his creator. He tells Kirk that the entities from the Andromadar nebular who have made them do not exist any more. Now they serve Harry Mudd. Spock suspect a central system which steers the 200,000 robots and finds Norman using it. He learns more about them. Meanwhile Mudd has brought down all the crew and beamed some robots on board. When he wants to leave himself he learns that the robots have taken all his positive inputs, but they want the ship for themselves and he is to stay with the crew on the planet. His commands to bring his suitcases are ignored. They inform him that he is not is charge, but he can rule as long as he likes -only he should not interfere with them. 

Norman says he cannot tolerate that the universe is ruled by those imperfect beings instead of by themselves. Now Spock becomes interested in how the robots are going to achieve their goal. Norman tells him that they will serve humanoids until they totally depend on the robots. Mudd is now in the same boat as they are. He had wanted to leave, too. As they discuss a strategy they come to the conclusion that the central system cannot possible steer all robots and Spock points out that there are several of each name, but there is only one Norman. Norman is the central leader of all. 

Kirk suggests that only behaving illogically can help. First they put Mudd to sleep. Kirk then calls a robot and tells her that Mudd is going to die. If they got onto the Enterprise they could help him in sick bay. Suddenly Mrs. Uhura comes forward and tells them that it is a trick to regain control and that Dr. McCoy only sedated him with an injection. The robot asks why she had helped him and Mrs. Uhura says that she wants a android body. When the robot has left Kirk congratulates her for her performance. They then perform a show which confuses the Alices because all in it is illogical. The plan works. Meanwhile Spock explains to two Alices how the machinery works. He gets a compliment: He’s astonishingly logical and has got an analytical mind. "Yes," Spock says, "I know" and gets closer to one Alice – only to find out that the Vulcan neck pinch does not work here. "What does it mean pressing my neck?" Alice 210 asks. "It means I love Alice 27 and hate Alice 210." "But we are totally identical, you will not notice any difference." "This is my logic: I hate you because you are identical." 

Both Alices get a fit and do not function any more. They keep on playing shows so that two by two the Alices break. In the end Norman cannot follow the madness either. He does not understand. And Kirk gives him the final blow: "I am not programmed to answer your illogical questions." Norman burns out. Mudd is left on the planet with all robots reprogrammed and 500 Stellas scolding him. McCoy asks Spock whether he is unhappy now. Spock denies for that would be a feeling, but McCoy goes on – the illogical humans have won against the logical robots. Isn't Spock unhappy to go back to be amongst all the illogical beings? Spock denies. There is no place, he's needed more.