Wolves of the Calla (The Dark Tower, Book 5)

[The Dark Tower][1] V

After escaping the perilous wreckage of Blaine the insane Mono and eluding the evil clutches of the vindictive sorcerer Randall Flagg, Roland and his ka-tet find themselves back on the southeasterly path of the Beam. Here, in the borderlands that lie between Mid-World and End-World, Roland and his friends are approached by a frightened band of representatives from the nearby town of Calla Bryn Sturgis. In less than a month, the Calla will be attacked by the Wolves--those masked riders that gallop out of Thunderclap once a generation to steal the town's children. The Calla folken need the kind of help that only gunslingers can give, and if the tet agrees to help, the town's priest--Father Callahan, once of 'Salem's Lot, Maine--promises to give them Black Thirteen, the most potent and treacherous of Maerlyn's magic balls. He used it to enter Mid-World, and now it sleeps fitfully beneath the floorboards of his church. Meanwhile, in the New York of 1977, the Sombra Corporation plots to destroy the lot at Second Avenue and Forty-Sixth Street. How can Roland and his friends both save the rose and fight the Wolves? Only by using the magic of Black Thirteen, but how can anyone trust this sinister and treacherous object which is, in actuality, the eye of the Crimson King himself? Time is running out on all levels of the Tower, but unless our ka-tet can defeat the minions of Thunderclap both in our world and in Mid-World, they will never reach that great lynchpin of the time/space continuum which, even now, begins to totter . . . ([source][2])

[1]: openlibrary.org/works/OL81600W/The_Dark_Tower_1-7 [2]: stephenking.com/library/novel/dark_tower_wolves_of_the_calla_the.html