Romantic suspense

The details are foggy because I read this more than 15 years ago.

I think moon was in the title. Not 100%. But from what I remember, a woman that was adopted as a kid returns home with her daughter so many years later. The love interest is like the "cousin" or something (not related). But it has some spelunking (exploring caves)in the story. Girls or women go missing and no one knows where they are. It turns out the uncle or someone like that has a place that is either like a secret shed or has an underground area where he keeps/perserves them. I think he turns them into dolls. He plans on doing it to her and her daughter.

I hope someone can help me find this. I've exhausted my search.

If there isn't a moon in the title, I think it might be on the cover.

There might be a lake.

There is spelunking.