'GOT' Season 7, Episode 7 Spoilers: 'The Dragon And The Wolf' Synopsis

The Night King and his army are officially more powerful than ever before with their new secret weapon on "Game of Thrones," making the need for all the enemy houses of Westeros to unite and fight against him all the more pressing.

Following the penultimate episode's shocking end, where the Night King (Richard Brake) managed to kill Daenerys' (Emilia Clarke) dragon Viserion, then resurrect him as a new member of the Army of the Dead, it's more pivotal than ever that Jon Snow (Kit Harington) get all the Lords of Westeros to unite with the Northern Army and fight when the dead finally make their way across The Wall and into their lands. The only way he can successfully unite the great houses of Westeros however is by proving the dangers the dead pose, which he will do in the Season 7 finale, "The Dragon and the Wolf."

In a preview clip for the episode, Jon, Tyrion (Peter Dinklage), Jaime (Nikolaj Coster-Waldau), Cersei (Lena Headey) and others will assemble in King's Landing for the summit that was requested so Jon could reveal the truth about the White Walker's existence.

"There's only one war that matters," he says in the clip. "And it is here."

The meeting is especially important in regards to Jon convincing Cersei that the White Walkers even exist, let alone how much of a threat they actually pose to the world that everyone knows. They hadn't been known to exist for thousands of years, and Tyrion previously stated that his sister, the reigning queen of the Seven Kingdoms, didn't believe they were real, and that they had simply been made up to scare young children with creppy stories.

Seeing a White Walker in person could quickly cause Cersei to believe in their existence, however, she may still have a new plot up her sleeve, as she isn't likely to trust anyone else, even if they all have a tentative alliance. Desperate to make sure she holds on to her throne, Cersei could make a shocking and unexpected decision about how to really handle the threat from beyond the Wall.

Meanwhile, Daenerys appears to be notably absent from the summoned crowd that is gathered together. However, at another point in the episode, Jaime and Bronn (Jerome Flynn) seem to find themselves at an undisclosed location, with Dany's Unsullied forces, who were previously stranded at Casterly Rock, assembled below them. The two also watch as the Dothraki tribes also arrive. It's unclear what this may be, but Dany may be making another move to try and get one step closer to the Iron Throne.

In Winterfell, the drama between Sansa (Sophie Turner) and Arya (Maisie Williams) will likely come to the ultimate point. Arya made some threats against her sister that indicated she would either kill her, or reveal how she once swore fealty to the Lannisters to discredit her amongst the Northern Lords. Now, Sansa may find a reason to actually visit with her brother, Bran (Isaac Hampstead-Wright), to see if he knows how to stop Arya from posing such a threat to her. In the process, she could learn just who the real threat to her safety actually is.

The "Game of Thrones" Season 7 finale airs Sunday, Aug. 27 at 9 p.m. EDT on HBO.