On the cusp of summer, angels--terrifying creatures of eyes and wings--have laid waste to human civilization, leaving a single survivor. Months later, Erika Cantor is alone in her hometown with no way to make sense of what's happened. Then a strange radio broadcast lures her into the grim outside world, a ruined place reclaimed by nature and inhabited by demons.

She soon encounters Midori, a secretive girl with a fondness for the angels. Then there's Gav, a strange boy determined to relentlessly follow Erika. He knows more than he should, but he refuses to answer any of...