The world is ending. His family is dead. And it's all the man's fault.

There's no reason for him to go on.

But he promised his eldest son that they'd explore the mountain cave near their home. They never got around to it, never enough time, always something in the way—work, school, other responsibilities, things that don't matter anymore. Now the man has all the time in the world, because everyone's out of time.

Of all the broken promises, this is the one he is determined to keep.

Along with the family dog, who he can't bear to leave behind, the man ventures into the cave.

Though he doesn't expect or plan for either of them to live very long, the man still struggles to keep himself and the dog alive, struggles to survive one more day, just one more day. Yet the deeper into the mountain they go, the stranger and more dangerous the cave becomes.

But that's the only thing left to do—go deeper.