Episode 4-1
Title: "Two Swords"
Directed by D. B. Weiss
Written by David Benioff & D. B. Weiss
Original Air Date -- April 6, 2014
Tywin Lannister oversees the reforging of Ice, the Stark ancestral sword, into two new swords. He gives one to his son Jaime, who tries and fails to return to his earlier life before the loss of his sword hand. Prince Oberyn, on the behalf of his brother, Prince Doran Martell of Dorne, arrives in King's Landing with his paramour Ellaria Sand to attend the royal wedding and is welcomed by Tyrion Lannister. Oberyn reveals his motive for his visit: revenge against the Lannisters for the rape and death of his sister, Elia. In the North, while Styr and his group of cannibal Thenns reinforce Tormund Giantsbane, Ygritte and the other wildlings, Jon Snow has returned to Castle Black and is released by Maester Aemon after confessing what he did during his stay with the wildings to gain information. Across the Narrow Sea, Daenerys Targaryen leads her army on a march towards Meereen, the last of the three great slave cities, though she is troubled by how her dragons grow less tame as they grow larger. In the Riverlands, Arya, accompanied by Sandor "The Hound" Clegane, reclaims her sword Needle from Polliver, and uses it to kill him the same way he murdered Lommy Greenhands, as retribution for her friend.
Source:
https://en.wikipedia.org/wiki/Game_of_Thrones_(season_4)