Joffrey makes Sansa kiss his new sword before he goes out to watch the battle. The noblewomen of the city gather in the sept at the castle. Sansa sees Ser Ilyn Payne, the executioner, standing with her father’s sword. Cersei tells her that Ilyn is there to protect them from treason and that Cersei’s own guards may turn on them. Sansa says that true knights would never harm women, and Cersei tells her to wait for some to show up.
Davos sails his ship into the bay at King’s Landing and up the river, where they will launch their attack. He is skeptical of the strategy that Stannis’s captains have decided to employ. Davos sees the winch towers for a giant underwater chain at the mouth of the river leading into the city. He realizes that the Lannisters mean to let Stannis’s ships enter the river, then close it off behind them, but he isn't sure what their strategy is and cannot understand why the Lannisters’ best ships are not present. The battle ensues. It is chaos as ships ram each other, arrows fly, and catapults fire stones down from the castle. The Lannisters launch wildfire onto the ships, which take fire. It looks to Davos like Stannis’s men are winning until one of Stannis’s ships rams an unmanned Lannister ship full of jars of wildfire. The resulting explosion and fire sweep across the ships, and Davos notices with horror that the chain has been raised, trapping the boats. The entire river is ablaze.
Tyrion watches from the castle as the wildfire burns through the Lannister and enemy ships. Some of Stannis’s men make it across the river to King’s Landing and fighting begins on land. Joffrey goes to the catapults, where they have rigged up traitors to fling at Stannis’s men. Tyrion tells Ser Osmund Kettleblack, a member of the Kingsguard, to keep Joffrey safe. Tyrion rushes to the King’s Gate, which Stannis’s men are trying to breach with a battering ram. He orders the Hound to take some men and attack them. The Hound refuses, afraid of the fire. Tyrion resolves to lead the sortie himself and convinces the other men to join him.
The women wait in the Queen’s Ballroom as the battle rages outside. Cersei tells Sansa that they will all be raped and possibly tortured and killed if Stannis’s men reach them before Stannis himself can arrive to impose order. Low-born people from the city ask for sanctuary, but Cersei has her men drive them off. Cersei orders Joffrey brought back into the castle, in spite of Tyrion’s orders. Cersei tells Sansa that the real reason Ilyn is there is to kill them before Stannis can get his hands on them.
Tyrion and his men attack Stannis’s force. They charge while everything burns around them, and Tyrion feels the battle fever that Jaime described to him. As they fight, the Lannister forces begin to cheer for Tyrion. The boats in the river are so closely packed that Stannis’s men are able march across them to the shore. Tyrion and his men move in, but Tyrion gets thrown from his horse. Tyrion loses track of what's happening and it seems that Stannis’s men are fighting two battles. Ser Mandon Moore, a member of the Kingsguard, moves as though he's going to help Tyrion but then slices him across the face. Tyrion realizes Mandon means to kill him. Then he sees Mandon disappear into the river and hears the voice of Podrick Payne, his squire, comforting him.
Lancel tells Cersei that when the men saw Joffrey returning to the castle, they lost heart. No one can figure out what is happening, as it looks like Stannis’s forces are fighting the Lannisters and each other. Cersei orders Joffrey brought inside despite Lancel’s objections. She storms out. Sansa comforts the wounded Lancel and some of the other women. Sansa returns to her chambers and finds the Hound waiting for her. He tells her his life there is over and says he could take her with him and protect her. The Hound puts his knife to Sansa’s throat and demands that she sing. She sings and gently strokes his face, finding it covered with tears. The Hound leaves, discarding his Kingsguard cloak. Dontos arrives and tells her that the city has been saved, that Tywin Lannister and Mace Tyrell and a huge army arrived to crush Stannis from the rear. Dontos claims that Renly's ghost led the army.