This is Metropolis, the novel that the film's screenwriter -- Thea von Harbou, who was director Fritz Lang's wife and a collaborator in the creation of the film -- this is the novel that Harbou wrote from her own notes. It contains bits of the story that got lost on the cutting-room floor; in a very real way it is the only way to understand the film.
Michael Joseph of The Bookman wrote about the novel: "It is a remarkable piece of work, skilfully reproducing the atmosphere one has come to associate with the most ambitious German film productions. Suggestive in many respects of the dramatic work of Karel Capek and of the earlier fantastic romances of H. G. Wells, in treatment it is an interesting example of expressionist literature. ... Metropolis is one of the most powerful novels I have read and one which may capture a large public both in America and England if it does not prove too bewildering to the plain reader."