The mystery story is not the most satisfying I have ever read. My complaints range from plot to style; the plot is held back too much until the end of story, so that the last few chapters are basically character monologues filling in the gaping holes in the mystery; the style was annoying in that the two main characters, two teenage girls who met on the beach, were too much in sync. I should clarify that second point: the dialogue between the two main characters reads more like an inner monologue of a very grammatically inclined person. There is very little done to differentiate the speaking styles of different characters, and there is too much foreshortening of the most interesting parts.
In short, I don't think I would recommend this to anyone looking for a mystery novel, though it does make for fairly furtive ground to those interested in adolescent literature.