Tell No One -- Harlan Coben

David Beck has rebuilt his life since his wife's murder eight years ago, finishing medical school and establishing himself as a pediatrician, but he's never forgotten the woman he fell in love with in second grade. And when a mysterious e-mail arrives on the anniversary of their first kiss, with a message and an image that leads him to wonder whether Elizabeth might still be alive, Beck will stop at nothing to find the truth that's eluded him for so many years