Deadly Vows by Keri Arthur

Evil comes in all forms … and sometimes it wears a human mask.

When the body of a newlywed is discovered on the reservation, Lizzie Grace throws herself into the investigation, needing a distraction from what she fears is coming not only for her but also Belle—her best friend and witch familiar.
But as the body count grows and a desperate race begins to track down a supernatural entity capable of powerful magic, it becomes evident another deadly game has begun—one they may not win.
Because the past—and the man—they ran from thirteen years ago has finally caught up with them.
And he’s out for revenge…