Nurse Edyth Fellows (Kate Reid) is being helicoptered into Stasis due to an emergency. She'd only recently been hired by Stasis Corporation, and asks her escort what the emergency is. Her escort declines to answer, saying that Dr Hoskins (Barry Morse) will explain everything once they get there. Stasis has actually locked onto a primitive human, something they were expecting to happen next week, and they're rushing to complete the transfer before their lock is lost. Miss Fellows watches in bewilderment as the Stasis team works to bring forward in time a neanderthal boy (Guy Big).
Excited, Dr Hoskins tells Miss Fellows that she will be the first civilized woman in history to care for a neanderthal child. Angrily, Nurse Fellows berates Dr Hoskins in private, not understanding why a nurse with her qualifications is being asked to take care of someone who isn't even human. Dr Hoskins explains the situation to her, and reassures her that this is a temporary experiment, lasting only two hundred days. After a moment's consideration, she accepts the new conditions of her employment.
A series of scenes follow, highlights from the two hundred days of the neanderthal experiment. Several different scientists, each accompanied by a personal nurse, examine the subject to learn about his physiology. Blood is drawn, x-rays taken, tranquilizers shot... as time passes, Nurse Fellows becomes more and more attached to the child, while the other scientists get more and more excited for the next phase of the experiment; bringing a medieval person, an adult they can converse with, forward in time.
Nurse Fellows immediately begins teaching Timmie to speak, and when she does, tries to convince Dr Hoskins that this means Timmie can stay in the present. Disagreeing, Dr Hoskins tells her that he plans to send the subject back tonight because they're ready to move forward with the medieval experiment.
"The Ugly Little Boy" provides examples of:
- Adaptation Distillation: Several of the subplots from the original Novelette were removed to streamline the story, such as Dr Hopkin's son, Jesse never appearing.
- Adaptation Name Change: Adapted from "The Ugly Little Boy", the following names were changed:
- Edith Fellowes becomes Edyth Fellows, as seen on her resume.
- Dr Hoskins loses his first name and ends up with Last-Name Basis because this adaptation cuts several minor plot elements.
- Timmie's proper name in the original story is Timothy, but the scene where Nurse Fellows names him is completely different, so she only gives him the Affectionate Nickname.
- Dramatically Missing the Point: Dr Hoskins describes the next step after the neanderthal child experiment; they will be bringing an adult from the medieval age forward in time. Nurse Fellows notices that he emphasised the way the medieval experiment will be able to talk, so she starts teaching Timmie to speak English so that Dr Hoskins would choose to keep him around, not realizing that the point of the experiment she named Timmie was to establish that they could bring a person forward in time with no ill effects. She was told from the start that the neanderthal experiment was in preparation for the later medieval experiment.
- "It" Is Dehumanizing: Dr Hoskins sees the titular child as an experiment only. He occasionally says "it" instead of "he", but most often simply calls him "the subject".
- Last-Name Basis: In a change from the original story, Dr Hoskins goes the entire time without using a first name, nor is it included in the credits.
- Motherly Scientist: In this adaptation, Edyth Fellows is chosen specifically for her lack of emotional connection because they don't want anyone becoming attached to the titular child. However, as the days of constant testing go by, she begins to resent the careless approach the other scientists have for the boy. Before the end of the 200 day experiment, Miss Fellows has become heavily attached to the child, naming it Timmie.
- Omniscient Database: Edyth Fellows was selected by the "young earth" computer from a pool of over five thousand applicants. She was chosen based on her professional skills and lack of personal relationships.
- Shown Their Work: One of the unnamed characters name-drops Solecki, an archeologist who discovered several neanderthal fossils. The child's traits, including rheumatism/arthritis, are based on the skeleton Shanidar 1.
- Tantrum Throwing: After a particularly painful testing session, the titular boy begins crawling up a wall with cubbyholes and smashing the glass bottles that he can reach on the ground until Nurse Fellows can calm him down.