The series is based on the novel of the same name. Midwich, a working-class town in England, is liberal, progressive, made up of small families and wealthy streets. Not much happens here, and for good reason. Until dusk one summer day, a quiet area of the town is in a state of panic. People faint without warning or reason, and anyone who tries to enter the area also experiences the same thing. No one understands why. When the mysterious power outage is lifted, the people affected by the incident gradually return to their normal lives, except that every woman of childbearing age in the area suddenly becomes pregnant. As the news spreads, the situation becomes increasingly tense, and people who have experienced this emotional shock need help, and talented psychotherapist Dr. Susannah Zellaby takes on this responsibility. Susannah's daughter Cassie is pregnant, and she is deeply concerned about the dark hand behind this phenomenon. Local police officer Senior Inspector Paul Kirby is responsible for maintaining order, but what people don't know is that a terrifying force is gathering in the town's peaceful streets. These children, who may be potential parasites, thrive under the care of their families. Who are these children? What do they want?