Apocalypse — Nancy Springer

A woman returns to wreak end-of-the-world vengeance on her Pennsylvania hometown 

Disfigured since birth, Joanie Musser has endured decades of taunts and torments from the “normals” in Hoadley, Pennsylvania. Her only friend is a boy named Barry Beal, who has an ugly birthmark on his face. A few days after Barry lends her $500 and his welder's mask, Joanie disappears.
 
Cally Wilmore, a vaguely discontented mother of two and the wife of the local funeral director, sees Joanie first: a breathtaking blond apparition galloping through town on a white steed.
 
Rebel and resident cynic Gigi Wildasin senses that something peculiar is happening. The cicadas are crying out of season -- modern-day locusts who swarm the town bearing dead children's faces -- and a blacksnake appears next to the most beautiful and erotic naked man anyone has ever seen. Cally and Gigi, along with Shirley Danyo and her lover, Elspeth, all ride horses to escape their everyday lives, unaware that they are the Four Horsewomen of doom. A familiar stranger has come to Hoadley with a terrible purpose, and for the inhabitants of this struggling coal-mining community, it seems that Judgment Day is nigh.
 
An allegorical novel about small-town prejudice and the secrets that fester beneath the surface, Apocalypse is also about the power of love to triumph against all odds.