Katsuhiro Otomo's epic adventure is set in mid-19th century England; London is the center of the Industrial Revolution that would soon sweep the world. Ray, who was born into a family of scientists, spends his days and nights in pursuit of new inventions. One day he receives a mysterious metal ball from his scientist grandfather. From that moment on, Ray is plunged into a world of intrigue and adventure. The metal ball is in fact a "steam ball," the heart of a mysterious and ominous "steam castle," and the secret key to a force of unparalleled power. But there are other parties eager to capture the steam ball, and the ensuing fight over it traverses land, sea and air, propelling Ray into the adventure of his life as he struggles to redeem his family and save London from destruction.