I was expecting a more traditional mystery than I actually got here, and I was also expecting a paranormal element for some reason.
This is a good story, though, for all that is is much more of a thriller than a traditional mystery. Things are definitely not always what they seem, and although I absolutely saw very early on (due to the multiple viewpoints, primarily) at least part of what must have happened, I was surprised by the full extent of what was going on. It was pretty dark and and awful, though the kind of awful that is comparatively mundane, I suppose, given what I was going in expecting.
Lucy is a decent main character, and the alternating viewpoint with her (long-missing) mother makes for a good central narrative. Both women are just naive enough that you genuinely believe they could end up in some of the situations in which they end up, but not so naive that they don't handle them in a relatively rational way.
Sorry, attempting to avoid spoilers sometimes requires awkward phrasing.
The setting was an important part of the atmosphere of the story; important enough that there are few places this could have happened left in the U.S. (not sure about elsewhere, admittedly): small, insular communities where outsiders are treated like aliens (in all senses of the word, I suppose); communities full of secrets that are not spoken of and bad things that aren't shared with the outside world. Stephen King and H.P. Lovecraft both wrote novels that shared this basic setting, and it lets this story take the step it needs from forgettable novel into a slightly eerie thriller.
In the end, I enjoyed it, and might pick up another novel by the author, but I'm not immediately going out and grabbing a bunch of them--if you're more into thrillers in general than I am, though, this might very much be your cup of tea.