With Cort poisoned by a book secreted into Gilead by the agents of John Farson, Roland imprisoned for the murder of his mother and the proleteriat of Gilead distrustful of the Gunslinger aristocracy over the death of their beloved Gabrielle Deschain, the Affiliation are in a precarious position.
Steven Deschain, Robert Allgood and Christopher Johns set out to capture an escaping Marten Broadcloak. Having tracked him to a solid wall of rock, they decide to return to Gilead, but are ambushed by a group of slow mutants with poisonous darts (and trained by Marten). Robert is killed by a dart after attempting to protect Steven.
Meanwhile, Cort dies in Gilead, leaving Aileen Ritter as the sole member of her family. She decides to forgoe the appearance of a women by cutting her hair, binding her breasts and wearing her stolen guns.
Justus, a double agent who is truly loyal to John Farson, convinces the Gunslingers to attack a Farson camp that he claims is undermanned and poorly defended. Also, a public trial for the still-imprisoned Roland is declared to placate the proletariat.
While the Gunslingers mount their attack on Farson's base, Dr Laird DeCurry and his medical staff are killed by John Farson's agents within the Gilead Guards.
The Gunslingers ill-fated assault on Farson's camp leads to their encirclement by Justus and his men, who attempt to take the Gunslingers, including Steven Deschain, captive. Not one for surrender, Steven Deschain calls his men to fight. Only Steven Deschain and Chris Johns survive the fight.
Upon his return to Gilead, Chris Johns discovers the scene at the infirmary of Dr Laird DeCurry and is murdered by the corrupted Gilead Guards at the scene.
At the same time, while reviewing the Plans of Gilead (including its hidden traps and pitfalls) drawn by Arthur Eld, Steven Deschain is stabbed through the chest by a corrupted Guard, and - having killed his assailant - dies. He leaves a message in his blood for Roland to "Open the Pits".
The remaining young Gunslingers (and apprentices) declare Roland their dinh, giving him his father's (and Arthur Eld's) Sandalwood Guns and the Horn of Eld. They plan the battle to defend Gilead and swear vengeance on John Farson.
Men of the city of armed with spare guns and the women, children and elderly are hidden deep within the citadel with access to the sewers for escape, should Gilead fall.
Cuthbert is placed in charge of levers that control the booby traps, with Alain relaying messages from the other Gunslingers to coordinate timing.
The first wave of slow mutants is killed by enormous spike-filled pits opened beneath their feet by Cuthbert; however, the bodies quickly form a path for the next wave.
As slow mutants attempt to scale the walls using grappling hooks, Cuthbert activates spikes that shoot out of the walls, impaling a number of mutants. However, the large number of mutants, seige towers and powerful Old Ones' technology (such as tanks and rocket launchers) overthrow the outer walls.
Having retreated to the inner keep, bladed walls and poisonous spiders are used to keep the attackers at bay, but Farson's bazooka troops make light work of the stone walls.
Meanwhile, the corrupt Guards gain access to the defenseless citizens in the citadel sanctuary and attack them with a flamethrower.
The Gunslingers retreat to the citadel sanctuary to find all the citizens have been killed by the corrupt Guards. With their flamethrower out of fuel, the Gunslingers kill them, ashamed that these were the men who had killed their fathers.
The battle ends with Marten replacing the flag of Gilead with that of Farson's eye sigul, and the few remaining Gunslingers escaping through the sewers.
The fall of Gilead precipitates the breaking of the first beam and a beam-quake, which almost swallows Sheemie. The beam which runs through Gilead (the Eagle-Lion beam) is understood not to have been the broken beam, as its magnetic properties remain.
Sheemie has a vision of the beams, represented by six boys, one carrying his dead brother, and all weakened and injured.
Roland declares his intention to follow the beam to its source (as he doesn't know the direction, he may be following the beam away from its source) - the Dark Tower, to seize its power and restore Gilead. His Gunslingers declare their devotion to his cause and announce they will all follow him on his quest, starting Roland's quest to the Dark Tower.