Hugo Cabret, a young boy, looks out from behind an enormous wall clock in a bustling Paris train station in the 1930s to watch the travelers moving about. He then races between the station's walls to check in on an old man minding his toy stall. Greeting the old man is Isabelle, a girl who looks to be about Hugo's age. After the old man dozes off behind his counter, Hugo emerges from a grate and attempts to steal a mechanical mouse. Only pretending to be asleep, the old man grabs Hugo's arm and forces the boy to empty his pockets of stolen goods. In addition to various tiny gears, Hugo also pulls out a notebook that contains drawings of a mechanical man. The notebook angers the old man and he threatens to burn it if Hugo doesn't reveal how he got it. The old man's demands ring so loudly that the mean Station Inspector hears and runs over. The terrified boy takes off without his notebook and, after a mad dash through the station, evades capture. At the end of the day, Hugo returns to the toy stall and confronts its cranky owner who continues to insist he's going to burn the notebook. Hugo follows the old man to his home. Throwing rocks at an upstairs window, Hugo gets Isabelle to come outside. He begs her to save his notebook and when she swears she'll absolutely keep it safe, Hugo goes back home to the station. Hugo then spends time with the real-life mechanical man that is pictured in the notebook. Flashing back to the past, Hugo recalls that his father, who brought the contraption home from his museum, called it an “automaton.” Father and son try to get it working again, but it won't until they find a special heart-shaped key to wind its gears. Unfortunately, the Cabrets' work is halted when Hugo's father perishes in a fire and the boy is sent to live with his drunken Uncle Claude, who works as the caretaker of the clocks at the train station. Back in the present, when Papa Georges returns to work, he hands Hugo a pile of ashes – the remnants of the notebook. Heartbroken, Hugo runs to Isabelle, who claims the notebook is perfectly safe. The ashes were just a trick to fool Hugo. Hugo continues to pester Papa Georges, who, impressed with the boy's ability to fix things, gives him a job working in the toy stall. Isabelle and Hugo also spend more time together. Since Papa Georges forbids Isabelle from going to the movies, Hugo sneaks her into a revival of Safety Last! , a silent comedy starring Harold Lloyd. Walking home, Hugo tells Isabelle the story of the first movie that his father said he ever saw. In it, a rocket ship flies through space and lands in the eye of the man in the moon. When they return to the station, Isabelle almost gets trampled by the rushing crowd. When Hugo comes to her rescue, he notices that she is wearing a heart-shaped key as a necklace, which they discover fits perfectly into the automaton's keyhole. Winding it up, the mechanical man comes to life and begins sketching on a piece of paper. While Hugo expects the automaton to produce a message from his dead father, he is distressed that the “drawing” is just a random collection of scratches. As the automaton continues to draw, though, a clear image forms: a rocket ship piercing the eye of the man in the moon along with the signature of Georges Méliès, which is “Papa Georges” full name. Hugo and Isabelle pester Georges' wife, Mama Jeanne, about the meaning of the drawing, but she refuses to say. When Papa Georges comes home, the children hide away and find a secret compartment in a bedroom armoire that is filled with similar drawings and paintings. Hearing their ruckus, Papa Georges is devastated to see his painful past being dredged up. Doing research at the film academy library, Hugo and Isabelle meet a film historian, Rene Tabard, who believes that Georges Méliès perished in the Great War. The children inform him otherwise and discover that Tabard is an expert on Méliès films. He shows the children his collection of artifacts from Méliès' former motion picture studio, which was a grand building made with glass walls to allow light in for filming. When Hugo and Isabelle ask to see one of Méliès' films, Tabard informs them that only one, out of hundreds he made, has survived over the years. That night, Hugo brings Tabard to Isabelle's home as a surprise to Papa Georges. Although Mama Jeanne politely asks the historian to leave, Tabard charms her by revealing that he recognizes her as an actress in her husband's films. As Papa George naps in the bedroom, Tabard unspools Méliès' Le voyage dans la lune , the film with the rocket and the man in the moon. When the movie ends, Papa Georges awakes and at last opens up about his past and how he began his career as a magician and tinkerer, building things like his beloved automaton. But, after wandering into an early film screening at a carnival, Papa Georges became inspired to build his own movie camera out of pieces from the automaton. He would then go on to write, direct, design and act in hundreds of movies filmed at his glass studio, including an Arabian knights adventure with a fake fire-breathing dragon. But then, after the Great War, audiences grew tired of watching Méliès' fantastical films. Made destitute, Méliès destroyed his studio and sold his films so that they could be melted down and transformed into ladies' shoe heels. With his last little bit of money, he bought the toy stall where he has worked ever since. The only thing that Méliès could not bear to destroy was the automaton, which he left at a museum for safe-keeping. At the end of Papa Georges' sad tale, Hugo runs off. Entering the train station, Hugo is pursued by the Station Inspector. Cornered at the very top of the station, Hugo sneaks out through an enormous outdoor clock and dangles from the large minute hand over the Paris streets, just like Harold Lloyd in Safety Last! . Unable to find the boy, the Inspector goes to search elsewhere, finally freeing Hugo to grab the automaton. Still, once Hugo gets to one of the train platforms, the Inspector grabs him and the mechanical man sails through the air to land on the tracks. Wiggling out of the Inspector's grasp, Hugo jumps down to rescue the machine. But, a train races into the station, threatening to flatten the boy and the contraption. Luckily, the Inspector reaches down and saves them both. As Hugo begs for his freedom from the Inspector, Isabelle and Papa Georges finally arrive. The old man declares that Hugo belongs to him and the Inspector lets the boy go. Much later, Professor Tabard introduces a special program honoring Georges Méliès at a packed Paris cinema. An exhaustive search has uncovered eighty "lost" Méliès films that have all been restored and are to be screened. When Papa Georges steps out from behind the curtain, he is greeted by a standing ovation. The grateful old man publicly thanks Hugo before the screening starts. Then, at a party honoring Méliès, Isabelle begins writing a book about her adventures with Hugo.