Harcourt Fenton 'Harry' Mudd
Roger C. Carmel

Stella Mudd
Kay Elliot

Norman
Richard Tatro

'Alice' series
Alyce and Rhea Andrece

'Herman' series
Tom and Ted LaGarde

'Barbara' series
Colleen and Maureen Thornton

'Maisie' series
Tamara and Starr Wilson

Lt. Rowe
Mike Howden

Ensign Jordan
Michael Zaslow

A new member of the Enterprise crew, Mr. Norman, subdues the crewman on duty in auxiliary engineering and resets the ship's course. In main engineering he single-handedly overpowers all the crew on duty and rigs the engines to detonate should any course-correction be attempted. He then makes his way to the bridge to confront James Kirk, assuring him that 'we' mean no harm and opening a panel in his chest revealing that he is an android.

He explains about the booby-trap device and that they should arrive at their destination in four days. Following this, he crosses his arms and turns himself off, reactivating when they achieve orbit around an uncharted planet. He orders Kirk to take a landing party down to the surface where they are collected by two, gorgeous, identical android girls who take them to a room to be greeted by the infamous galactic entrepreneur, Harry Mudd.

Harry explains to Kirk that he had a slight misunderstanding with some Denebians and a navigational fault brought him to this planet where he found himself to be the centre of attraction for 200,000 androids who wanted to wait on him hand and foot. His current problem is that they won't let him leave, as they want to study him. His only means of escape was to give them someone else to study - the captain of a starship.

He shows them a special android that he has designed, a copy of his nagging wife Stella, the woman who drove him into space, and proudly demonstrates how she shuts up when told to. The androids inform Kirk that they were created by a race called 'The Makers' and only a few locations survived when their culture collapsed. They had been without purpose until Harry Mudd arrived and gave them someone to serve.

Mudd demonstrates some more of his android designs to Uhura and Kirk, offering her the tempting opportunity of living for 500,000 years in an ageless android body. The entire crew of the Enterprise is forced to beam down and are replaced by androids. They are all very impressed with the service they receive from the androids and by the facilities available, which worries Kirk, who is wondering how he can get control of his ship back. When Mudd tries to leave for the ship the androids stop him, saying that they cannot allow such a greedy and destructive race to run around the galaxy as they please. They plan to keep him and the Enterprise crew on the planet and use the starship themselves.

Kirk and the others discuss their situation, with Scotty commenting that androids are not capable of creative thought. Spock suggests that their minds are all co-ordinated by the Norman android as the rest are all 'series' androids whereas there is only one 'Norman'. They formulate and carry out a plan to start acting strangely and illogically, which includes the acting out of a bizarre mime show. This causes the androids to start seizing up as they try to make sense of what is happening.

Finally, Kirk and the others confront Norman with a stream of illogic and paradox, which ultimately fuses his brain, rendering the other androids leaderless. Kirk and the crew return to the Enterprise but Harry is told he must stay behind and provide an example of human failure to the androids, which have been re-programmed for productive work. He discovers that they have also left him a special 'present' - five hundred Stella androids that do not shut up when told to.