Plot

Because of an unusual disorder that has aged him four times faster than a typical human being, a boy looks like a 40-year-old man as he starts fifth grade at public school after being homeschooled.

Jack Powell was born with a unique disorder that causes him to age four times faster than people usually age, so when he's 10 years old he looks 40. This causes problems when he starts public school and tries to make friends with his classmates.—Bob Gohari <bgohari@earthlink.net>

The film begins as Karen Powell (Diane Lane) goes into labor during a Halloween party and is rushed to the hospital by her husband, Brian (Brian Kerwin), and their friends. Although the delivery is successful, the baby is extremely premature, born after only ten weeks of pregnancy. Strangely, the infant seems to be a normal, healthy, full-term baby. After examinations and tests, the infant, now named Jack, is found to have an exaggerated form of Werner syndrome. Dr. Benfante (Allan Rich) and Dr. Lin (Keone Young) diagnose a very rare autosomal recessive disorder. Their prognosis is that Jack will develop and age at a rate four times as fast as an average child, rendering him "sick as frig" as Dr. Lin explains colloquially.

Jack (Robin Williams) is next seen ten years later as a ten-year-old boy in the body of a forty-year-old man. Four boys lurk outside his house, swapping rumors of a "monstrosity" of a boy their age who can't go to school. He scares them away by dipping a fake eye into slime and throwing it at them from his window. He is extremely childish due to his secluded life. He has only socialized with his parents and his tutor, Lawrence Woodruff (Bill Cosby), who introduces the idea that he should go to public school. His parents initially balk, for fear Jack could be emotionally hurt.

When he first attends school, he is cast away by several kids since he looks like a 40 year old man. His dad later gives him some encouragement and both agree to install a basketball hoop to help him fit in. At school the following days, Louis picks him on his team to play basketball with some bullies and they win the game. After school, Louis asks Jack to help him by pretending to be the school principal to help him look good in front of his mom Dolores (Fran Drescher). Afterwards, they become friends and invites him to a clubhouse with other kids, having him eventually get adult magazines and other such adult items for his group of friends. He attempts to be a normal kid, but when he deals with his first crush, and heartbreak of confessing to his teacher, Miss Marquez (Jennifer Lopez), he falls down a flight of stairs while attempting to leave, and is rushed to the hospital. His doctor explains that he suffered a shocking severe strain (which could've been a rare form of angina), and also, because of his Werner syndrome, his internal clock is starting to run out. Realizing the dangers it might entail for his health, his parents decide to withdraw him from school, which upsets him.

He sneaks out of the house and goes to a bar, where he gets drunk and befriends a man named Paulie (Michael McKean), and tries to hit on Dolores. However, he gets into a fight with a bully (Edward Lynch) and both are arrested. Dolores bails Jack out, and comforts Jack after dropping him off home. Upon returning home, he locks himself in his room and doesn't go out for weeks. Karen speculates that perhaps he realized the fragility of his life and is now scared of facing the outside world again. He also doubts the need to study as he realizes that he wouldn't have the time to use any of the knowledge.

Meanwhile, his friends continue coming to his house, hoping that he will come out and play, but he refuses. Finally, Louis has an idea: he brings the entire class over as they take turns yelling "Can Jack come out and play?" and participate in various games and fun activities right in front of the yard. The next day he decides to go back to school.

Seven years later, an elderly-looking Jack and his four best friends are at their high school graduation. He delivers the valedictory speech, in which he reminds his classmates that life is short, and urges them to "make your life spectacular," as the five of them drive off into the future. (C) Description 2020 Wikipedia.