Out of Sight — Carrie Boyer

It's the holidays and Jill Tanner, PI is as busy as everyone: she has her favorite purse ruined by radiation exposure from a stolen credit card someone tried to use at The Vault (it belongs to a Peruvian diplomat rumored to have had his young wife murdered); she tries to help an undocumented family robbed of their household goods and Christmas gifts; and, she receives an anonymous threat against a childhood friend on a Christmas postcard: the image of one of these friends has been blotted out, and on the back is written the word SOON! Plus, she needs to finish her Christmas shopping. And it appears that someone is following her. Jill must race against time to figure this out and prevent deadly consequences, as these events all seem related, like a backward puzzle where the pieces obscure the whole picture.