In a prosperous city named Russell City, an omen that threatens to shake its world begins to move within it. A man named Sword is the first to hear the first stirrings of the plot, and throws himself into a shadow war in order to expose it. His only clue is the key word "El Dorado." He meets Sophie, a woman searching for her missing older brother who has only left her with the same words: "El Dorado." With Sword having also lost his younger sister in the past, both are drawn together by the words, and work together to find out its meaning.