If you sit a spell, and look just so, you might catch a glimpse into another world, or several. Some seem no different from the world you call home, give or take a monster waiting in the shadows, or an avenging angel hidden in plain sight, or an inhuman forest spirit better left undisturbed. Other worlds may be unrecognizably strange, from storybook kingdoms to ash-strewn apocalypse. Familiar or far-flung, all these worlds have...