Devastated and exhausted, Eden Lucas is the sole survivor of an unfathomable global catastrophe As she grapples with the question of whether to go on alone, a train arrives.

It's not a normal train, that's the first thing she notices. For one thing, it's floating three feet off the ground in a supermarket parking lot. For another, there doesn't seem to be any place for the driver to go. Yet it seems to hint at possibilities. Maybe she's not the only one who was spared. Maybe someone on the train will have answers.

And while she may yet discover what caused the death of her world, nothing can prepare her for just how little she understands about the universe.