Nightwood — Patricia Windsor

Casey, Gena, and Maryann can think of a way better use of a week than a senior trip to Washington, D.C. Casey's plan is simple. Ditch the trip to D.C., camp out at her parents' amazing cabin in Delonga, and accidentally "run into" Lane and his friends on their fishing trip. She knows the boys will be across the lake--her friends will thank her once they're up there.
Three girls for three boys will be the perfect party. After all, what could be more fun than five days in the woods? No curfews, no rules, and no parents. No one will even know they're up there.
And no one will hear them when they scream for help.
When the first body shows up, it's shocking. When the knock comes on the back door, it's horrifying. And when they realize there's nowhere to hide, they'll wish they were already dead.
Surviving a week in the woods is a going to be a whole lot harder than these girls could ever imagine.