Elijah Price is born in 1961 in a Philadelphia department store. The doctor present notes his frailty even while still in the womb. He is diagnosed with Type I osteogenesis imperfecta, a rare ailment that renders sufferers’ bones extremely fragile. Elijah, whose condition prevents him from participating in any physical activity alongside his peers, thus spends his early childhood in solitude.
One day in 1974, now thirteen-year-old Elijah’s mother persuades him to cross the street from their apartment, where she gives him an old comic book. He becomes a fan almost immediately, and spends his spare time reading superhero comics. While he can’t emulate his favourite characters, he becomes well versed in comic book tropes, and his actual job as an adult is the next best thing to super-heroism for a comic book lover like himself: he sells art based on it. Meanwhile, he develops twin theories that comic books are actually historical records of real-life superhumans’ activities, if with a bit of embellishment, and that if he breaks at the slightest provocation, someone who’s “unbreakable” under even the most extreme duress might exist to complement him.
In the present, David Dunn is a Philadelphia security guard, whom we meet as he returns home by train from New York City, where he had been at a job interview. His marriage to his wife Audrey is failing, giving him some dread in returning home. He flirts awkwardly with the attractive young woman seated next to him … which ends abruptly when the train crashes, killing her and everyone on board except David. Doctors at the hospital where David is taken tell him that not only is he the sole survivor out of 132 people on the train, he sustained no harm in the crash.
Learning of David’s improbable survival, Elijah invites him to his store. Elijah suggests David survived because he is actually a real-life superhero. David laughs off the possibility, but then Elijah asks him how many days of his life he has been sick. He asks Audrey, their son Joseph, and his boss, if he’s ever taken ill, and none of whom can remember such. (The boss, thinking David’s question is a demand for a raise disguised as a joke, gives it — albeit only another $40 per week.)
Although he doubts having any special abilities, David begins to test himself. Much to his shock, he discovers that he can bench-press 350 pounds. While Joseph is impressed and convinced of David’s superhuman attributes, David remains unsure. Exacerbating his anxiety, Joseph, thinking he might have some superhuman traits of his own, gets into a fight with a bully at school that ends unwell for him.
Meanwhile, David meets with Elijah at the college football stadium where he works. There, he realizes he can actually see into people’s minds when they make contact with him, learning that a drug dealer has just been active and scaring him off his “job” for the day. Elijah falls down a flight of stairs, sustaining several injuries that require weeks of physiotherapy to mend.
David tells Elijah that, since he almost drowned as a boy, he cannot be a superhero. Elijah replies that most comic book superheroes have a single weakness, and contends David’s is water. This prompts David to re-evaluate his past again; he then remembers that he gave up playing football in college because Audrey disapproved of its violent nature. He had crashed his car, supposedly injuring himself, but to the extent he got hurt, it was when he fell into a nearby lake.
Remembering that he can sense people’s intentions, David goes to Philadelphia’s Thirtieth Street Station, where he stands in the lobby and lets people bump into him. Through contact, he learns of crimes they have committed, and decides eventually to pursue a sadistic janitor who invaded a family home, killed the parents, and is now holding the two children hostage. David visits the crime scene and frees the children, but the janitor ambushes him and tries to drown him in the swimming pool. The children come to David’s aid, giving him the upper hand by distracting their former captor. David kills the janitor and reconciles with Audrey the same night. The next morning, he shows a newspaper story on the incident to Joseph, who recognizes the drawing of the man in a rain jacket as his father.
David attends an exhibition at Elijah’s comic book art gallery and meets Elijah’s mother, who explains to him the difference between villains who fight heroes physically and those who use their intelligence. Elijah invites David into his office, congratulates him on having discovered his identity, and shakes hands with him. As they do, David’s ESP-like ability shows him, to his horror, that Elijah perpetrated several disasters, each of which resulted in mass fatalities, including David’s train crash. Elijah insists his actions were justified on the grounds that, since he could never be a hero, he had to become a villain. He explains that his fate was sealed after the two men met and became friends, since comic book heroes and villains tend to be polar opposites and yet remain friends: “I should have known way back when. You know why, David? Because of the kids. They called me Mr. Glass.”
Screen captions explain that David reported Elijah’s actions to the police, and Elijah was charged with several counts of murder and terrorism and sent to an asylum for the criminally insane.
