[Ghostlike creatures in the desert...it's a lot to take in. But given the things he's already seen in this world, Yu isn't inclined to doubt the truth of it. If it is what really happened...he starts to feel a nervous knot tying in his chest.]

If they were, it means something pretty bad happened to them.

[No doubt about that. He can't blame William for hoping that's not the case.]

But that would leave the question of who they are...and what happened to the original residents, too.