Hugo is an orphan boy living in the walls of a train station in the 1930s in Paris. He fixes clocks and other gadgets as he learned to from his father and uncle. The only thing that he has left that connects him to his father is an automaton that doesn't work; Hugo has to find its heart-shaped key. On his adventures, he meets with a cranky old man who works in the train station and his adventure-seeking god-daughter. Hugo finds that they have a surprising connection to his father and the automaton, and as he discovers it, the old man starts remembering his past and his significance to the world of film-making.