The movie follows the imaginative boy Tom as he continually gets into mischief and causes accidents locally with his chemical experiments. The townspeople regard him as a troublemaker. As the Civil War breaks out, Tom starts a business enterprise peddling food and snacks on board trains, and later composing and handing out news sheets to passengers. In a stroke of inspiration, Tom at night cleverly focuses light from multiple lamps onto a large mirror, enabling a surgeon to successfully operate on his mother. The story ends with Tom desperately signaling in Morse Code with a train whistle, alerting the engineer of another train filled with passengers to stop before it plunges into a river. These two acts finally vindicate Tom who is now a hero.