The Dark Tower” episodes will center on “Wizard and Glass,” the fourth book of the series, and will co-star Idris Elba as The Gunslinger himself, Roland Deschain. Elba will serve as a narrative framing device for flashback events that take place before the movie. “The Dark Tower” director Nikolaj Arcel and co-writer Anders Thomas Jensen will provide at least some of the scripts for the show’s 10 to 13 episodes, although they will not be serving as showrunners. “The Dark Tower” hits theaters on February 17, 2017.