Missandei gives Grey Worm a lesson in the Common Tongue, and they recount being taken into slavery as children. Grey Worm tells his tutor he has no desire to return to his homeland; he only wants to "kill the masters." Later that evening, Grey Worm leads his army, disguised as slaves, to infiltrate Meereen through the sewers. The Unsullied rally the Meereenese slaves to take the city. As the liberated masses call out to Daenerys Targaryen, she ignores Barristan Selmy's advice to show mercy to the slavers. In retribution for the dead slave children who marked the road to the city, Dany orders 163 masters crucified.
Jaime visits Tyrion in the Black Cells after Bronn chastises him with a story: Bronn only stood for Tyrion at the Eyrie because his first choice, the Kingslayer, wouldn’t have made it in time. Jaime confirms his brother's suspicions about Cersei – she wants Tyrion dead. Tyrion asserts his innocence, but Jaime can do little to help him or Sansa, whom Cersei is convinced also played a part in Joffrey’s murder. When the queen regent learns of Jaime's visit to the dungeon, she summons her twin and questions his loyalties.
Aboard Littlefinger's ship, Sansa finds out it’s headed to the Eyrie. Confronted by Sansa, Littlefinger confesses he had a hand in Joffrey’s death. He reveals to Sansa she played a part as well – the “heirloom” Ser Dontos gave her contained the poison that killed the king.
In the Red Keep, Margaery is shocked to learn Olenna Tyrell orchestrated the assassination to save her granddaughter from marrying Joffrey. Olenna shares a narrow miss of her own: Originally engaged to a “twitchy” Targaryen, she changed her destiny by wandering into Luthor Tyrell’s chambers and stole away her sister’s fiancé. Now it's Margaery's turn to "do what needs to be done," Olenna states. That night, Margaery pays a late night visit to Tommen, who is dazzled by his intended.
Jon Snow schools the Night's Watch recruits in swordplay. Roose Bolton's henchman Locke, posing as a recruit, impresses Jon with his fighting skills. Irked by Snow's initiative, Alliser Thorne shuts down the training session and reminds Jon that he is a steward. Janos Slynt points out to Acting Commander Thorne that the bastard is popular within the Watch and an election lies ahead. Slynt suggests Thorne approve the mission to capture Craster's Keep and "let the mutineers take care of Snow."
Samwell Tarly worries for Gilly, fearful that Mole's Town will be the next village raided by wildlings. Jon Snow commiserates about their orders to remain at Castle Black; he's anxious to find Bran. Realizing his brother might seek shelter at Craster's Keep, Snow presses the issue with Thorne, who sanctions the operation. Jon asks for volunteers to join him, reminding the men that if they are indeed brothers, then the Lord Commander was their father. Locke volunteers and his vows are expedited so that he can accompany Snow.
At Craster's Keep, Karl commands Rast to feed Ghost, Jon Snow's direwolf, who is caged outside. The mutineers are distracted when Craster's wives request "a gift for the gods." Karl acquiesces and orders that Craster's last son, a newborn baby, be sacrificed to the White Walkers. Rast apprehensively leaves the infant in the woods.
The baby's cries carry to the campsite of Bran, Hodor and Meera and Jojen Reed. Bran wargs into Summer to investigate, but ends up jeopardizing the group and the foursome is captured. Karl interrogates the hostages and learns Bran's true identity.
A White Walker claims the baby and rides to a city of ice. The child is presented at an altar, where a Walker greets the infant and lays a finger on its cheek. The baby's eyes turn White Walker blue.
Jaime Lannister presents Brienne Tarth with his Valyrian steel sword and a new suit of armor. Brienne must use the gifts to uphold her vow to Catelyn Stark and find Sansa. Although she's less excited to receive the service of Podrick Payne, Brienne accepts him as a squire. In the spirit of the mission, Brienne names her sword “Oathkeeper.”
Daenerys successfully captures Meereen amidst a slave revolt, and immediately seeks justice for the slain slave children by nailing 163 masters to posts. At sea, Petyr admits to Sansa that he was responsible for poisoning Joffrey, despite his alliance with the Lannisters. In King's Landing, Olenna also intimates to Margaery that she ordered the poisoning, and encourages Margaery to seduce Tommen before Cersei has a chance to turn him against her. Jaime meets with Tyrion, and is convinced he is not guilty. However, Cersei is adamant about Tyrion's guilt, and orders Jaime to hunt down and kill Sansa. Jaime instead tasks Brienne with finding and protecting Sansa, and sends Podrick along with her. In the North, in an effort to get rid of Jon, Alliser Thorne and Janos Slynt conspire to allow Jon to lead an expedition against the Night's Watch mutineers occupying Craster's Keep. Meanwhile, Bran and his party stumble upon Craster's Keep, where they are captured by the mutineers, and Bran is forced to reveal his identity to them. Further north, a White Walker takes Craster's last newborn son to a secret ritual site, where another White Walker touches the baby's face, turning its eyes blue.