Wen and her dads are taking a break from everything by visiting a remote cabin for vacation. Wen is studying grasshoppers in their yard when a man comes up and makes friends with her. He warns her that she and her dads are going to have to make a decision. And that's about all I can tell you without spoiling you.
This book was SO creepy in a very good way. I'd classify this as horror, but in a very real way.
The Cabin at the End of the World by Paul Tremblay ($26.99*, St. Martin's Press), recommended by Bookmiser, Inc., Roswell, GA.