Ned Stark is beheaded and Cersei and Joffrey quickly flee the scene. However, Arya witnesses the beheading and pledges to avenge Ned's death.
Oh dear. It is okay, son. It had to be done. No one will know.
What have I done?
Quick, son; we must go.
He did not deserve to be beheaded. What will Sansa say when she finds out?!
Oh no! Ned! They will pay for this.
Time goes by and Joffrey is convinced that he is safe from anyone finding out about him beheading Ned. With the power he attains as the new king, Joffrey abuses his power by treating the servants and maids cruelly.
I am the new king and you will do as I say!
Yes, King Joffrey.
Meanwhile Joffrey continues to abuse his power as king, Arya ventures off to the Hound to train in order to dethrone Joffrey.
I am trying!
Come on, now! Do not hesitate. You need to take charge.
After several months of training and preparation, Arya is ready to take on Joffrey. With the Hound by her side, Arya marches towards Joffrey's castle.
Thank you for everything. Will you come with me to defeat Joffrey?
I believe that you are ready now.
Arya arrives at Joffrey's castle and challenges him to a sword fight. Joffrey accepts, letting his overconfidence get the best of him and putting up a poor fight.
JOFFREY! Your reign is over! Accept your doom, coward!
Ha! You cannot do anything. My reign is forever and that is inevitable. You are only a girl - powerless.
Arya kills Joffrey, ending his dreadful reign. Therefore, Arya avenges her brother and saves the kingdom from Joffrey.