The Sorcerer goes by many names. In Gilead, he is known as Marten Broadcloak, but he has had others... Walter O'Dim, and Randall Flagg to name but a few. He describes sorcery as stacking the deck of fate, and so he works to bring about the fall of Gilead. The last descendants of Arthur Eld, the Deschains stand between Marten and the Dark Tower.

But as his plans draw to a climax, his closest ally betrays him. The spirit of the sphere known as Maerlyn's Grapefruit bewitches Roland Deschain, leading him to slay his mother (and Marten's lover) Gabrielle. Alas for Marten's plans, Gabrielle was supposed to kill her husband, leaving Gilead ripe. Now, John Farson's forces will have to fight to destroy the kingdom.