Callie's older sister is a saint. And not one of those people who just do nice things and people say that about them, Tess is actually being considered for sainthood by the Catholic church because she has performed miracles. While she was alive she heard voices that helped people coming to Tess for answers so people were already praying to Tess for help even before she died of a rare heart condition. Now that she is gone the pressure to find a miracle she has performed is even greater. Callie knew her sister best of all and she knows that Tess didn't think of herself as a saint so Callie is determined to prove she wasn't. Before she died a young girl was kidnapped and everyone looked to Tess for clues to finding the girl. Now Ana has been found at one of the many shrines set up to Tess and the whole city is whispering "miracle". But Ana isn't talking at all and the person who took her is still watching.
This is a dense story packed with so many layers that it's difficult to unpack. There is: Callie's grief and her reaction to that; her mom's determination to prove Tess is a saint; Callie's relationship with Tess' boyfriend (who was a secret from the rest of the world); Ana's recovery; the process of sainthood; what faith means; the mystery of who took Ana and where he still is; about ten more things as well! I liked most of it but I got frustrated with Callie's self-destructive behavior even as it was clear why she was acting that way.