After his mother is killed by the ruthless robot Count Mecha, young Tetsuro turns into a delinquent street urchin who harbors a single desire: revenge. In a distant future, humanity can travel to another planet where they can trade their bodies for immortal, robotic counterparts. Tetsuro plans to acquire enough money, by theft, to board the Galaxy Express 999, a space‑faring train that will take him to the planet of robots. One day, while evading the police, he encounters Maetel, a beautiful woman who bears a striking resemblance to his mother. She offers to accompany him aboard the Galaxy Express 999, promising him a robotic body and the chance to confront Count Mecha.