What is the importance of Chapter 28? (Consider it from the novelist's working viewpoint.)

In chapter 28 of To Kill a
Mockingbird, Lee marks the culmination of her Gothic suspense.  In a novel
that begins in SUMMER, it is apropos to end it in FALL during HALLOWEEN
to reflect its Gothic motifs.  The supernatural ghost Boo saves the children
at night in the woods against the maniacal Bob Ewell.  The mockingbird defeats the blue
jay.

Lee wants to connect her characters in the resolution.
 She begins her book with Jem's broken arm as a frame, and she focuses on Tom's mangled
hand during the climax of the trial.  Jem and Tom, both mockingbirds, are victimized by
cruelty.  Injuries are important in the Southern Gothic tradition to show the damaging
effects of an illegitimate society.  The gothic tension that Lee worked so hard to
develop in part I of the novel comes full circle as Boo shows his face, and Scout learns
that he's not so grotesque after all, the lesson that Atticus has stressed time and
again.