Shadow Creek — Joy Fielding

When an innocent group of campers ventures to the Adirondacks for a trip, they are followed by a murderous pair...

A group of unlikely traveling companions--a woman, her two oddball friends, her teenage daughter, and her soon-to-ex-husband's new fiancee--find themselves on a camping trip in the Adirondacks at the same time that a pair of teenage killers is terrorizing the area.