Several years after the fall of Gilead, Roland leads the last remaining Gunslingers in harrying the forces of the Good Man, John Farson and pursuing their quest for the Dark Tower. But as they travel along the Beam, hoping they're travelling in-world to the Tower, Farson's men stand between them and their goal.

And Farson's men have not been idle. They're attempting to resurrect the ancient machines of war left behind by the old ones. And against these weapons, even the firearms of the Gunslingers can not stand.