This episode of Outer Limits begins with a young woman, named Cathy, walking up to an imposing manor. She enters the building and walks into the laboratory of Professor Mathers (Doctor Grump).
Actually, this begins with a clip from later in the episode with a big headed alien dude who telepathically attacks two police men. But, it won't make much sense at this point.
So Cathy has brought some bread for Mathers, and the two get to talking. Brought up in their conversation is the professor's new machine, capable of enhancing one's natural intelligence through hyper-evolution. As of this point, he has only used it on Darwin, his chimpanzee. Cathy expresses a desire to try it, because she believes that she isn't smart enough already. It falls through as she has the wrong blood type.
The professor really likes the bread, so Cathy leaves to get more. At the store, she gets berated by the shopkeeper for having improper change. Then, dun da da dun, two coal miners to the rescue! One of them is Cathy's boyfriend Gwyllm (Will), who goes back to the lab with her.
Will becomes assistant to Mathers and the first human subject for the machine. He enters it and the professor begins the sequence. The key control is a large lever with the options 'Forward' and 'Backwards'.
The run is successful, with the cosmetic additions of a larger forehead and a small sixth finger on both hands. Will now has a greater thirst for knowledge and is rather pushy about it. "Give me all of your books!"
Gradually, the former miner becomes a bald headed alien with psychic powers, and loses his morality and compassion. He wages battle against the town, referring back to our two officers from before.
Cathy and Will go to the lab, where he gives her the order to take him to the max, as far as the machine will go, thus turning him into an intellectual vortex. The lady does not go through with it, and pulls it back instead. Our guy starts reverting and with some wigging out, he is back to himself. The episode ends with Cathy comforting Will, who has collapsed from the strain. Or is he dead? It didn't appear that way.
Not all human experiments receive that type of ending, happy or without complete face heel turns. (The Fly, The Lawnmower Man, Hollow Man, every horror and/or sci-fi flick ever. Except for Altered States.)