Everywhere That Mary Went by Lisa Scottoline

Mary DiNunzio is trying to make partner in her cutthroat Philadelphia law firm. She's too busy to worry about the crank phone calls that she's been getting—until they fall into a sinister pattern. Mary can't shake the sensation that someone is watching her. Following her every move. Then the shadowboxing turns deadly, and she has to fight for something a lot more important than a partnership—her life.