The photo on the card shows a boy who was found murdered, a year ago, on the grounds of a girls' boarding school in the leafy suburbs of Dublin. The caption says I KNOW WHO KILLED HIM. Detective Stephen Moran has been waiting for his chance to get a foot in the door of Dublin's Murder Squad -- and one morning, sixteen-year-old Holly Mackey brings him this photo. "The Secret Place," a board where the girls at St. Kilda's School can pin up their secrets...