The Girls Weekend by Jody Gehrman

Their reunion just became a crime scene . . . June Moody, a thirty-something English professor, just wants to get away from her recent breakup and reunite with girlfriends over summer break. Her old friend and longtime nemesis, Sadie MacTavish, a mega-successful author, invites June and her college friends to a baby shower at her sprawling estate in the San Juan Islands. June is less than thrilled to spend time with Sadie--and her husband, June's former crush--but agrees to go. The party gets off to a shaky start when old grudges resurface, but when they wake the next morning, they find something worse: Sadie is missing, the house is in shambles, and bloodstains mar the staircase. None of them has any memory of the night before; they wonder if they were drugged. Everyone's a suspect. Since June had a secret rendezvous with Sadie's husband, she has plenty of reason to suspect herself. Apparently, so do the cops. A Celtic knot of suspense and surprise, this brooding, atmospheric novel will keep you guessing as each twist reveals a new possibility. It will remind you of friendships hidden in the depths of your own past, and make you wonder how well you really know the people you've loved the longest.