Episode 4-9
Title: "The Watchers on the Wall"
Directed by Neil Marshall
Written by David Benioff & D. B. Weiss
Original Air Date -- June 8, 2014
The Night's Watch prepare for the coming invasion by the wildlings. Gilly arrives at the Wall shortly before Mance Rayder's army. The wildlings attack from both sides, with one army climbing the Wall, and Ygritte's army attacking Castle Black. After Ygritte and her army get through, a bloody battle ensues. The wildlings attempt to break through the tunnel leading into Castle Black with the help of several giants and a woolly mammoth, but are stopped by Grenn and five others, who die holding the tunnel. Alliser Thorne goes down to the main level of Castle Black to fight, leaving Janos Slynt in charge. However Slynt proves to be incompetent as a commander, and is tricked into going down the main level, effectively leaving Jon in charge. Pyp is shot by Ygritte and dies in Sam's arms. After watching Jon kill Styr the Thenn, Ygritte prepares to kill Jon, but is shot by Olly. Jon holds Ygritte in his arms as she dies. With the help of Jon's direwolf, Ghost, the ground level of Castle Black is secured by the Night's Watch. The wall climbers are sliced apart and completely obliterated from a massive scythe that acts as the Wall's secret weapon. The wildlings retreat, but, Jon predicts, not for long. Seeing no other choice, he goes beyond the Wall to find and kill Mance.
Source:
https://en.wikipedia.org/wiki/Game_of_Thrones_(season_4)
Game of Thrones - Season 4, Episode 9 Synopsis
