The book takes place in a world that is recognizable as the American West but in an alternate timeframe or parallel universe to ours; Roland exists in a place where "the world has moved on". Roland is a Gunslinger, a trained assassin and expert marksman with a fatal obsession.
The Gunslinger takes the form of a series of interleaved flashbacks, as Roland's quest is interrupted with dreamlike vignettes from his youth. By far the most stylized and enigmatic of King's longer works, the book is perhaps best seen as an introductory tableau or prologue to the entire series, the subsequent books of which are much more concrete and linear in their story-telling.
Originally written when King was only 19, The Gunslinger was first published in 1982 as a limited edition, with its first mass-market publication as a trade paperback in 1988 followed by several re-issues in various formats and in boxed sets with other volumes of the series. In 2003 the book was reissued in modified form, with scenes added and other changes made to resolve inconsistencies with the later books in the series.