At first Sam and Flora aren't even afraid. They live in a future so deep it may as well be the past. They greet neighbors in the marketplace. And the town enjoys a respite from winter. But the warm spell turns monstrous, swallowing horizons. So this man and his wife dig a hole and hide at the bottom of the world. They leave behind those threads of life and cut through roots and clay. Flora is the architect of their survival. But in the heat she gets weak, wispy like clouds. Sam finds a puzzle while they work. A message in tiled letters, buried for ages in the earth. What does it mean to say, from so far away? The question of it haunts him. And with the embers of their love dying, Sam and Flora must choose how to embrace their bitter end. But there are miracles yet to be found, at the bottom, in the dark. Can Sam and Flora survive the end of the world? What waits for them if they do? Because something else is surviving too. A million years above, the threads of life they left behind begin to writhe and change.