Thirteen-year-old Jessie Keyser likes to accompany her mother, a midwife, to homes where there are births or illnesses. Her father is a blacksmith. She and her five siblings live in a log cabin in a small village. They believe the year is 1840. What Jessie doesn't know is that she lives in a replica of a 19th-century village and that the year is actually 1996.

When local children begin to fall ill of diphtheria, Jessie's mother takes her into the woods, provides her with food, blue jeans and a T-shirt, instructions on how to use a telephone, and amazing stories of the world outside that she and Jessie's father left when they joined the experimental colony. Jessie learns that tourists view them at their daily activities through hidden cameras. Now she is to escape and get needed medicine.

Armed guards surround the village. Safely outside the gates, Jessie wanders disoriented in 1996, looking for someone safe to ask for help. She finally talks to reporters who broadcast the news and send help immediately to the town. Medicines are brought and some children saved, though diphtheria has taken several lives. Jessie enters the present with some ambivalence, realizing there are large tradeoffs to leaving the simplicity of the past.