They Are the Hunters - Faith Gardner - Bog

The family that slays together, stays together.
The Hunters appear to be the textbook definition of a perfect family leading a charmed life. When the enigmatic Olivia West befriends teenage daughter Eliza, Olivia becomes one of the family-an "honorary Hunter."
Here's what they don't know about Olivia: she's planning a murder. And whether they like it or not, every member of this family is going to become an accomplice.
And here's what Olivia doesn't know about the Hunters: they've killed before. And if Olivia threatens their reputation, they will absolutely kill again.