Teru and Ako finally escape the tunnel, but the mystery of whatever caused their horrible train crash only deepens when they find nothing but ruins, abandoned buildings, and unending gloom above ground. Soon, however, they see suspiciously human—like shadows slinking about and chase after them in a last-ditch effort to find someone—anyone—else alive. But even friendly faces conceal their own darkness, and sometimes the people we implicitly trust can turn out to be the most dangerous of all.