The first part of the novel, The Fabulous Idiot , narrates the birth of the gestalt. In the beginning, we are introduced to the world of Lone, referred to as the "Idiot", a 25-year-old male with a telepathic ability who lives on the street. He knows he can make people do what he wants them to, but has never experienced real human connection. One day he encounters Evelyn Kew, an innocent woman who has been completely sheltered by her domineering father. She is the first person he has mentally and physically connected with. Evelyn's father finds out about the relationship and kills Evelyn and himself. During this incident Lone barely escapes a beating from the father; bleeding and nearly dead, he is found and then adopted by the Prodds, a poor farming couple, and lives with them for about seven years. When Mrs. Prodd becomes pregnant, the couple are about to ask Lone to leave, but he makes his departure appear to be his own idea. Lone builds a shelter in the forest and is soon joined by three runaway children: Janie, an eight-year-old with a telekinetic gift, and the twins Bonnie and Beanie, who cannot speak but possess the ability to teleport. Lone returns to the farm to find Mrs. Prodd has died after giving birth to a "Mongoloid" baby. Lone adopts the baby, who has a phenomenal mental capacity and thinks almost like a computer. Together, Lone, Janie, the twins and Baby form what will be later called the homo gestalt . Prodd's old truck is always getting stuck in the mud, and when Lone asks Baby for a solution, Baby helps Lone build an anti-gravity generator. He installs it in Prodd's truck, only to find that Prodd has left for Pennsylvania.
The second part of the novel is Baby is Three , which occurs several years after The Fabulous Idiot . Gerry Thompson, a street urchin who has grown up in abusive institutions, is possibly sociopathic. He consults a psychiatrist, trying to piece his memory back together. Gerry ran away from the institution and was taken in by Lone. Lone was killed in an accident and Gerry subsequently became the leader of the gestalt. Lone had instructed the kids to seek out Evelyn's sister, Alicia, after his death. They were educated and fed under her care. Soon, however, Gerry learned that domestication and normalization had weakened their gestalt. He killed Alicia, and the group returned to living alone in the woods. If anything, Gerry's telepathic abilities are stronger than Lone's. His amnesia was caused by Alicia's having accidentally transmitted her memories to his mind when they first met, triggered by her strong emotional reaction to hearing the words "Baby is three". He learned about her entire life, including her past relationship with Lone, in a split second. After being helped by the psychiatrist, Gerry erases the man's memory of him.
The third and concluding part of the novel is Morality . Again, it occurs several years after the previous part. Lt. Hip (Hippocrates) Barrows is a gifted engineer who worked for the US Air Force until the incident which led to his incarceration, first in an insane asylum, then in jail. Janie, now an adult, befriends him and helps him regain his health. He slowly remembers what had happened. He discovered some odd effects on an anti-aircraft range. Practice shells fired in a certain area were all duds. Barrows does magnetic tests and finally discovers the anti-gravity machine, still on the rusted-out old truck on the nearby farm. Gerry knows of Hip's investigation and poses as a common soldier assisting Hip, then launching the anti-grav into space and stopping Hip from saving it. He then mentally attacks Hip to make him look insane, driving him to a mental breakdown and amnesia, Gerry does this because Baby has told him that if the anti-grav was discovered, it would lead either to a terrible war or to the complete collapse of the world economy. Gerry is determined to drive Hip permanently insane. Hip confronts Gerry, and becomes the last part of the gestalt, its conscience.