As Robb Stark and his northern army continue the war against the Lannisters, Tyrion arrives in King's Landing to counsel Joffrey and temper the young king's excesses. On the island of Dragonstone, Stannis Baratheon plots an invasion to claim his late brother's throne, allying himself with the fiery Melisandre, a strange priestess of a stranger god. Across the sea, Daenerys, her three young dragons, and the khalasar trek through the Red Waste in search of allies, or water. In the North, Bran presides over a threadbare Winterfell, while beyond the Wall, Jon Snow and the Night's Watch must shelter with a devious wildling.

In the wake of a bloody purge in the capital, Tyrion chastens Cersei for alienating the king's subjects. On the road north, Arya shares a secret with Gendry, a Night's Watch recruit. With supplies dwindling, one of Dany's scouts returns with news of their position. After nine years as a Stark ward, Theon Greyjoy reunites with his father Balon, who wants to restore the ancient Kingdom of the Iron Islands. Davos enlists Salladhor Saan, a pirate, to join forces with Stannis and Melisandre for a naval invasion of King's Landing.

At the Red Keep, Tyrion plots three alliances through the promise of marriage. Catelyn arrives in the Stormlands to forge an alliance of her own, but King Renly, his new wife Margaery, and her brother Loras Tyrell have other plans. At Winterfell, Luwin tries to decipher Bran's dreams.

Joffrey punishes Sansa for Robb's victories, while Tyrion and Bronn scramble to temper the king's cruelty. Catelyn entreats Stannis and Renly to forego their ambitions and unite against the Lannisters. Dany and her exhausted khalasar arrive at the gates of Qarth, a prosperous city with strong walls and rulers who greet her outside them. Tyrion coerces a queen's man into being his eyes and ears. Arya and Gendry are taken to Harrenhal, where their lives rest in the hands of "The Mountain", Gregor Clegane. Davos must revert to his old ways and smuggle Melisandre into a secret cove.

The end of the Baratheon rivalry drives Catelyn to flee and Littlefinger to act. At King's Landing, Tyrion's source alerts him to Joffrey's flawed defense plan and a mysterious secret weapon. Theon sails to the Stony Shore to prove he's worthy to be called Ironborn. In Harrenhal, Arya receives a promise from Jaqen H'ghar, one of three prisoners she saved from the Gold Cloaks. The Night's Watch arrive at the Fist of the First Men, an ancient fortress where they hope to stem the advance of the wildling army.

Theon completes his master stroke. In King's Landing, the Lannisters send Myrcella off to be married. Arya comes face to face with a surprise visitor. Dany vows to take what is hers. Robb and Catelyn receive crucial news. Qhorin gives Jon a chance to prove himself.

Jamie meets a distant relative. Daenerys receives an invitation to the House of the Undying. Theon leads a search party. Jon loses his way in the wilderness. Cersei counsels Sansa.

Theon receives a visitor. Arya asks her third and last passing from Jaqen. While Stannis' army is reaching its destination, Davos is offered a reward. Betrayal befalls Robb.

A massive battle rages for control of King's Landing and the Iron Throne. Tyrion and the Lannisters fight for their lives as Stannis' fleet assaults King's Landing.

Tyrion awakens to a changed situation. King Joffrey doles out rewards to his subjects. As Theon stirs his men to action, Luwin offers some final advice. Brienne silences Jaime; Arya receives a gift from Jaqen; Dany goes to a strange place; Jon proves himself to Qhorin.