Inaccessible and mysterious, the jungle is the soul of South America. But probing it with the knife blade of civilization are men determined to run a railroad through its very heart: the aging English engineer whose humanity has been replaced by cynicism and obsession; the young American doctor whose romantic illusions dissolve with the first scorpion in his shoe; the beautiful woman who loses her grand piano and her husband to the pitiless river, but finds bizarre passion in a camp of horrors. And with them comes a smoke-belching train called Mad Maria, whose destination is nowhere, whose absurd journey is a darkly comic drama of man's fractured visions and shattered ideals.