"The North Remembers."
Word of Jon Snow's return spreads quickly. He wants nothing to do with leading people. His death and reanimation did change him. He is no longer willing to die for what he believes is right, because he "knows" there is nothing after life. But when he realizes what folks have done to his family (The Red Wedding, Ned beheaded, Sansa thrice-married and raped, Arya missing, Bran missing, Rickon missing), he will be re-purposed. He will take his followers to Winterfell to negotiate Rickon's release. Ramsey will hold Jon Snow's army at bay by threatening Rickon, but will not be able to help himself and will put an arrow through Rickon in sight of Jon Snow, as a challenge to Jon Snow. At that point, Jon Snow snaps and lets loose the dogs of war; meaning, The Red Witch, Brienne, Arya, his direwolf, the Wildings, Northerners still loyal to the Stark family, even some of the IronBorn, to boot. Ramsay ends up on one of those "X" torture devices and is flayed, dismembered, burned and fed to the wild animals. Although poetic justice would also allow Sansa to shiv the son of a *****, herself.
Somewhere in the process, we learn Jon Snow is Dany's nephew, Tyrion Lannister is revealed to, somehow, actually be a Targaryen, and voila, we have riders for all three dragons. The battle with the White Walkers is joined.
Meanwhile, the Lannisters. Gregor Kilgane (The Mountain) crushes (literally) the High Sept priest, Tommen is killed (fulfilling the prophecy made to Cersei when she was a child), Jamie Lannister renounces the Kings Guard and becomes King, for the time being.