Published on June 8, 2004, Song of Susannah is not the type of stand-alone horror novel that made Stephen King one of the world's bestselling authors. Instead, it is the sixth book of a seven-volume series titled "The Dark Tower." The series was completed over the course of more than thirty years; King wrote the first sentence of what would become the series' first volume, The Gunslinger, in 1972, and the final volume, itself titled The Dark Tower, was published on September 21, 2004. The series has its share of what readers have come to expect from King: page-turning suspense, horrifying evil in the form of both humans and monsters, gore, and often unpleasant fates for both good characters and bad.

But there are many other elements mixed in, including a J. R. R. Tolkien-style fantasy realm called Mid-World, where King presents large-scale battles, sorcery, and strange creatures like Oy, a kind of talking dog called a billy-bumbler. Also influential are 1960s spaghetti westerns starring Clint Eastwood, on whose "man with no name" King drew for the series' gunslinger hero, Roland Deschain. There are borrowings from science fiction, including robots and a thematic concern with the dehumanizing effects of modern technology. And there is realistic drama: one main character, Brooklyn-born Eddie Dean, must overcome heroin addiction.

All these styles and genres merge into an epic quest, pitting Roland against evil forces that would topple the Dark Tower and destroy the universe.