The Underworld in a Story's Third Act

The underworld, even more so than the normal world or the adventure world, is utterly symbolic. Unless you are faithfully recreating a myth, such as that of Hercules or Coyote, the underworld in your story will not be literal. But the stakes well be life or death. This life and death confrontation may be literal, as in many action stories such as True Grit or The Hunger Games or The Avengers. By this point, the character could not return to who she was in the first act, even if she wanted to. If there is any change at all within the story, and if there isn't, that's at best unusual, unusual. There will be at least the ghost