Game of Thrones season 7 is now premiering in high summer 2017—perfect weather to destroy a 700-foot-tall wall of ice, snow, rock and magic. The Wall has protected the Seven Kingdoms for eight thousand years or more, but its days are numbered. By the end of the series, and probably by the end of season 7, the Wall has to come down. It’s quite an image to close the season out on, if it ends up happening that way. But what comes after? What happens to the North after the Wall is gone?

Game Of Thrones Season 7: Life After The Wall

We don’t know how exactly the Wall is going to come down—just that it will. Only its fall can raise the stakes in the final war between the White Walkers and humankind, and its collapse has been foreshadowed heavily. Will the Night King bring it down? Or Bran , or Samwell Tarly, or—most likely of all—Euron Greyjoy? We don’t know yet. But once it falls, the Night’s Watch is clearly ended. Their force is already minuscule; they have little hope of holding off further attacks from the North even with the Wall. Without it, all their castles but the Nightfort are defenseless.

The most obvious consequence of Mr. Night King tearing down that Wall is the invasion of the North by the White Walkers. But what does this mean, exactly? The North is a huge place—the size of the other six kingdoms put together. And the White Walkers aren’t exactly fast.

Let’s say that by the time the Wall falls, Daenerys is back in Westeros, and her war is going apace. At some point, she must—presumably—turn her attention away from fighting with Westeros to take on this threat. She has to either win quickly or set her war aside, or ignore the threat and let the White Walkers kill everyone—not actually all that unlikely an outcome. After the Wall is gone, Daenerys could hurry North and take on the Night King’s host post-haste—but chances are the information will take some time to travel, and their army will start to head south.

First, the northernmost castles—the Last Hearth, Karhold and the Dreadfort—will fall. Possibly Deepwood Motte as well. The first major fortress in the North, of course, is Winterfell itself—now firmly back in Stark hands. Assume everything north of there is lost. But will the last stand take place at Winterfell, or will that just be the first outlay in the war? It’s hard to know.

The next choke point for stopping the White Walkers is Moat Cailin and the Neck, where the children of the forest tried to stop the First Men from conquering the North thousands of years ago with their spells. They tried to break the Neck and turn it into open ocean, but failed. It may be time to try again—somehow.

If the White Walkers get beyond the North, there’s serious trouble ahead. Most of the population of the Seven Kingdoms is in the South, and the riverlands would be open to them. It’s a terrible fate to imagine. The Westerosi’s best chances of stopping the White Walkers remain in the North—but they’ll need Daenerys to do it. She better hurry up and marry Jon Snow, or there’s going to be a real mess on everyone’s hands when the Wall comes down.