Harriet and David are not your typical young couple by 1960s standards; they are quite old fashioned. The sexual revolution is passing them by and Harriet is suspicious of the pill. After meeting at an office party, the two find that they have much in common. They are immediately attracted to each other and marry soon after meeting. Although they intend to wait a few years before having a family Harriet quickly becomes pregnant. The child is the apple of their eye and brings their extended families together more. Their home becomes a magnet for joy and enthusiasm for life; a second child follows, then a third, and a fourth. They are a happy family, even though money is a little short. Harriet's sister, Sarah, starts to feel frustration that because Harriet has children that she cannot afford, she also gets more help and attention from their mother, Dorothy. Sarah asks Dorothy to stop helping Harriet for a while and to help her instead. Dorothy agrees. Sarah's husband, William, also expresses the family's feeling that Harriet and David should not have any more children.
Harriet tells the family that they intend to take a hiatus from having more children, but will then try for baby number five. When that time comes, the pregnancy is a far cry from the previous four. Harriet is uncomfortable from the start and the baby moves around so much that it seems it is trying to kick its way out of her belly. A son, Ben, is born at eight months. There is no immediate connection between Harriet and her new baby. He is strange looking and there are whispers that he might be more changeling or gnome than human child. Ben is an aggressive baby. He pulls his brother Paul so hard through the rails of his crib that Paul's wrist is almost broken. She confines Ben to a room on his own because he is a threat to the wellbeing of his siblings.
Dorothy watches Ben for a week whilst the rest of the family take a vacation together. It is a cathartic trip and they find their happiness in each other again, but when they return home, Dorothy tells them that eighteen month old Ben needs to be institutionalized. David agrees but Harriet is resistant; she devotes herself full time to Ben, neglecting her other children, and he seems to make some progress. He starts to speak but seems to be mimicking his siblings when it comes to social cues and empathy with others; it does not seem to be coming directly from him.
When Ben turns three years old he starts stalking animals with the intention of hurting them. This prompts the family to return to the idea of institutionalizing him; the family feel immediate relief once he has left the home, but Harriet cannot stand the thought of him being in the institution alone, and so decides to pay him a visit. What she finds at the institution sickens her; Ben is lying on his cot, comatose, dressed in nothing but a straitjacket. She takes him home immediately which terrifies the rest of the family. Ben takes a shine to the family's landscaper, John, and Harriet offers John the position of nanny, which he accepts.
Ben starts school once he turns five; Harriet is on tenterhooks waiting for a call from the school to tell her that Ben has hurt someone, but to her surprise, he does very well. Teachers like him, and although he is struggling academically, they can see that he is trying hard. His first few months goes well and he makes some friends, Unfortunately it doesn't last; in his second semester he bites a little girl in his class and pushes her to the ground. breaking her arm in the process. The children's doctor organizes an appointment for Ben with a psychologist, who tells Harriet that she obviously doesn't like Ben very much, and he is picking up on this and acting out. He is open to the suggestion that Ben is not entirely human, but refuses to elaborate on this idea further. He gives Harriet sedatives to calm Ben down.
The older siblings decide that they do not want to stay at home whilst Ben is there, and they go to live with their grandparents. After the Christmas break, Paul starts seeing a psychologist to help him deal with his feelings of abandonment due to Harriet's emotional neglect of him.
By the time Ben turns eleven years old, he has made some friends at school. He brings home four friends whom Harriet at first assumes are friends with her son out of some kind of benevolent pity; she is surprised to see that far from being the sympathy buddy, he is actually the leader of the group. The four disappear off for days sometimes, and Harriet cannot help but notice that when they do, petty crime in the area increases.
David and Harriet decide to sell the house and move out of the area, and David tells Harriet not to tell Ben where they are going. Of course she does, but he seems unmoved by her overtures of keeping in touch; he barely looks at the paper with their address written on it. They are disconnected from each other emotionally, and so the geographical disconnect really changes nothing for either of them. Harriet wonders what will become of Ben; she cannot decide if he has really found his people in his group of friends, or whether he is mimicking a connection with them in the same sociopathic way that he has always done.
