Robb Stark shows his mother his plan to take Casterly Rock from the Lannisters. With so much at stake, he asks Catelyn for her advice; her instincts were right about Theon. Catelyn, grateful to have regained her son's trust, advises moving forward.
The Stark army arrives at the Twins and Robb, Talisa, Catelyn, Edmure and Blackfish are welcomed as guests by Lord Walder Frey. Robb apologizes profusely to Lord Frey and the women in his family for breaking his promise to marry one of them. Walder scoffs at the king's contrition and ogles Talisa. Despite the tense exchange, Walder pledges to put the past behind them.
The wildlings scout out a stone hut owned by a man who breeds horses for the Night's Watch. Orell, Tormund and Ygritte propose killing the man. When Jon Snow objects, suspicions arise. The wildlings race toward the hut, but Jon clanks his sword on a rock to alert the man, then distracts Ygritte mid-shot so she misses her target.
The Reeds, Bran, Rickon, Hodor and Osha take shelter from the downpour in an abandoned tower. The Reeds spot the fleeing horse breeder and the wildlings in pursuit. Hodor threatens to blow their cover when he shouts in panic, fearful of thunder. Reflexively, Bran's eyes flutter into the back of his head, immediately subduing the frantic giant.
Outside, the wildlings surround the old man. They task Jon with killing him as a test of loyalty. Because Jon hesitates, Ygritte ultimately does the deed. The wildlings realize the truth: Jon is still a crow. He's encircled by wildings and Tormund restrains Ygritte as a bloody fight ensues. With Jojen's encouragement, Bran wargs into one of the Stark direwolves and lunges to defend his brother. Orell wargs into his eagle right before Jon kills him. Shielding himself from the eagle, Jon rides off, abandoning Ygritte.
Daenerys Targaryen is counseled by Daario Naharis in her camp outside of Yunkai. He proposes her two best fighters enter the city with him through the back gate, so they can kill the guards and open the front gate for her army. Jorah is skeptical of Daario's intentions, but Grey Worm, making the decisions for the Unsullied, finds Daario trustworthy.
Moving forward with the plan, Daario leads Grey Worm and Jorah into the city. The three men fend off the Yunkish guards. A worried Dany paces until their successful return - aware of what happened in Astapor, the slave soldiers surrendered. Daario presents his queen with the flag of the city.
The Hound and Arya come upon a pork cart driver en route to the Twins. The Hound knocks the man out but reluctantly relents when Arya begs him not to him. As they approach the Stark camp, Arya is restless. The Hound calls her out - she's afraid they won't make it. Arya reveals that she knows his fear of fire, and promises to murder him one day.
Samwell Tarly forges a plan for him and Gilly: They'll head to the Nightfort where they can walk through a secret passage to the other side of the Wall. Gilly is impressed by Sam's knowledge and is awed to gaze upon the Wall.
Bran grasps the power of his gift when Jojen informs him that no other person can get inside a human's mind. Bran's commitment to find the three-eyed raven is affirmed. Aware that Castle Black might be under attack, he sends Rickon and Osha to Last Hearth to seek refuge with their bannermen, the Umbers. The youngest Stark is devastated to leave his brother, but Bran knows that Rickon's safety is paramount-if anything happens to him, his brother is the heir to Winterfell.
Edmure Tully is overjoyed when his bride is unveiled and he sees how attractive Roslin is. The two are married in the Faith of the Seven; a boisterous reception follows. Filled with drink, the Blackfish excuses himself. Once Edmure and Roslin are carried out as part of the traditional bedding ceremony, Black Walder closes the doors to the banquet hall and the band begins to play "The Rains of Castamere." Outside of the castle, the Hound and Arya are denied entrance into the celebration.
Lord Frey beckons Robb forward, and aware that something is amiss, Catelyn realizes that Lord Roose Bolton is wearing chain mail under his clothes. She calls out to Robb, but the massacre begins. Lothar Frey stabs Talisa repeatedly in the abdomen. Archers in the rafters rain arrows on the Stark attendees, wounding both Catelyn and Robb. The onslaught continues in the Stark camp outside. Arya watches the Frey men kill Robb's direwolf, Grey Wind. "It's too late," the Hound tells her before he knocks her unconscious and carries her away.
Catelyn uncovers a knife from the floor and grabs Lord Walder's wife from under a table. Now with a hostage, she begs for mercy, offering to forget and forgive everything so long as her firstborn is spared. Unmoved, Lord Walder shrugs and Catelyn looks on as Bolton stabs her son. Despairing, Cat kills the Frey girl and stands motionless with shock and grief until her own neck is cut.
Sam and Gilly arrive at the Wall. During a thunderstorm, Bran enters Hodor's mind to calm him down. Nearby, Jon refuses to kill an innocent man, so Tormund orders him killed. Bran uses his warg ability to save Jon, and Jon kills Orell then escapes, leaving a furious Ygritte behind. Osha, Rickon and his direwolf depart for the Last Hearth, while Bran and his remaining company plan to head beyond the Wall. Daenerys sends Jorah, Daario and Grey Worm to infiltrate Yunkai and open the city gate for her army. Yunkai soon falls to her forces. Robb arrives at the Twins and apologizes to Walder Frey, who feigns acceptance. Edmure marries Roslin Frey, but during the wedding feast, Walder Frey's men murder Catelyn, Talisa and most of the Stark bannermen, while Roose Bolton kills Robb. Arya also arrives at the Twins and witnesses a part of the massacre, but the Hound knocks her unconscious and carries her to safety.