A metropolis sometime in the future. The entire underground rail system is in the hands of a totalitarian transport corporation. Herold used to work as an engine driver for the corporation, but was fired following an accident. The ex-driver wants nothing more than to go back to work; one day, a young man named Karl who was a former colleague, gets in touch. The cor-poration's infallible computer has seconded Herold for a suicide mission: he is to dare the impossible and drive the train through the city's prohibited sector. When the engine breaks down on the underground railway, Herold begins to suspect what he has let himself in for.