Shadows on the Sand

Jack Wallace and her family have just arrived at the family's summer cottage. The "Beach" is located in Ontario, Canada, on the clean, clear shores of Georgian Bay. Jack and her friends have put aside all their concerns about school and homework to concentrate on the more important aspects of the summer- swimming and having fun!
The summer routine seems to have a wrinkle in it when an odd group moves into the cabin at the top of the ridge. What is it about these people that both intrigues Jack and sets her nerves on edge? Why are they so odd... or are they? Maybe Jack is just being a bit over sensitive.