The Greek Odessy

This book is about 3 girls that go to Greece. They meet this mysterious man there. He is a photographer named Demetri. He follows them around a lot. He keeps trying to take their passports so he can look at what they look like, but they dont want him too, so he keeps following them. Eventually he follows them into a Greek cave and threatens to kill them unless they let him look at their passports. He said he wanted to take their passports so he could sell them to people and they could put their photo in there and go to america. I wonder if they will give him their passports.....Or else....