The story is told through a series of journal entries written by the story's protagonist, Charlie Gordon, a man with a low IQ
of 68 who works a menial job as a janitor in Donnegan's Plastic Box Company. He is selected to undergo an experimental surgical technique to increase his intelligence. The technique had already been successfully tested on Algernon, a laboratory mouse. The surgery on Charlie is also a success, and his IQ more than doubles.
He realizes his co-workers at the factory, who he thought were his friends, only liked him around so they could tease him. His new intelligence scares his co-workers, and they start a petition to have him fired, but when Charlie learns about the petition, he quits. As Charlie's intelligence peaks, Algernon's suddenly declines—he loses his increased intelligence and mental age, and dies afterward, buried in the back yard of Charlie's home. Charlie realizes his intelligence increase is also temporary. He starts to experiment to find the cause of the flaw in the experiment, which he calls the "Algernon–Gordon Effect". When he finishes his experiments, his intelligence regresses to its original state. Charlie is aware of, and pained by, what is happening to him as he loses his knowledge and his ability to read and write. He tries to earn back his old job as a janitor, and tries to revert to normal, but he cannot stand the pity from his co-workers, landlady, and Ms. Kinnian. Charlie states he plans to "go away" from New York and move to a new place. His last wish is for someone to put flowers on Algernon's grave.
The novel opens with an epigraph
taken from Book VII of Plato's The Republic
Anyone who has common sense will remember that the bewilderments of the eye are of two kinds, and arise from two causes, either from coming out of the light or from going into the light, which is true of the mind's eye, quite as much as of the bodily eye.
Charlie Gordon, 32 years old, lives with phenylketonuria
and demonstrates an IQ
of 68. His uncle has arranged for him to hold a menial job at a bakery so that he will not have to live in a state institution
. Desiring to improve himself, Charlie attends reading and writing classes at the Beekman College Center for Retarded Adults; his teacher is Miss Alice Kinnian. Two researchers at Beekman, Dr. Nemur and Dr. Strauss, are looking for a human test subject on whom to try a new surgical technique intended to increase intelligence. They have already performed the surgery on a mouse named Algernon, resulting in a dramatic improvement in his mental performance. Based on Alice's recommendation and his motivation to improve, Nemur and Strauss choose Charlie over smarter pupils to undergo the procedure.
The operation is a success, and within the next three months Charlie's IQ reaches 185. However, as his intelligence, education, and understanding of the world increase, his relationships with people deteriorate. His co-workers at the bakery, who used to amuse themselves at his expense, now fear and resent his increased intelligence and persuade his boss to fire him. Later, Charlie confronts his scientific mentors about their condescending attitude toward him, particularly Dr. Nemur, because Charlie believed Dr. Nemur considered him a mere laboratory subject and not human before the operation.
When not drinking at night, Charlie spends weeks continuing his mentors' research and writing reports which include observations of Algernon, whom he keeps at his apartment. Charlie's research discovers a flaw in the theory behind Nemur and Strauss's intelligence-enhancing procedure that could cause him to revert to his original mental state. His conclusions prove true when Algernon starts behaving erratically, loses his own enhanced intelligence, and dies.
Charlie tries to mend the long-broken relationships with his parents. He remembers as a boy his mother insisted on his institutionalization
, overruling his father's wish to keep him in the household. His mother, who still lives in the family's old home in Brooklyn, has developed dementia
and recognizes him only briefly; his father, who broke off contact with the family years earlier, does not recognize him at all. He is only able to reconnect with his now-friendly younger sister, Norma, who had hated him for his mental disability when they were growing up, and is now caring for their mother in their newly depressed neighborhood. When Norma asks Charlie to stay with his family, he refuses but promises to send her money.
Despite regressing to his former self, he remembers he was once a genius. He cannot bear to have his friends and co-workers pity him. He decides to live at the state-sponsored Warren Home School, where nobody knows about the operation. In a final postscript to his writings, he requests that someone put some flowers on Algernon's grave in Charlie's former backyard.