This is one of my favorite books of all time. I read everything by Mary Stewart and love them all, but this book is the one I reach for every summer. It is set in Greece, and it always makes me desire to hop on a plane and fly to Greece, even though the setting adds to the fearfulness in this book.
By the way, the old movie has absolutely nothing to do with the book, even though it says it does. If I were Mary Stewart, I would have been appalled at what the movie makers did to her wonderful story.