After Destiny — Tanya Lisle

Even before the world ended, everyone inside the Janus Complex knew that the earth outside was flat. When the mountain appeared on the horizon that morning, they sent a small team out to see if it was really there or if it was just a trick of the haze.

When that team came back, the mountain was gone. The only proof they have that it was ever there at all are some soil samples, plants and insects who somehow managed to survive the irradiated haze, and a strange woman with no name who knows just a little too much about the people she has never met and everything that is about to happen to them.