What the Dead Know by Laura Lippman

Two sisters disappear in 1975. Thirty years later a mysterious woman shows up and claims to be one of them. Is she? I'm not telling. I did sort of figure it out about 2/3's of the way in but there was still enough doubt to keep me second-guessing myself. I do like the way she writes - she gives each character a chance to be in the first-person so you really get to see things from every angle and everybody's perspective.