The last thing rare book dealer Julia Wainwright wants is a baby-sitter. The threatening letters have been bothersome, but not enough so to warrant a private investigator who isn’t one. Julia strongly suspects that the letters are a direct result of her erotic novel writing. Her father, a local religious leader, is totally unaware that his daughter writes erotica, and she would like to keep it that way. Aware that Julia is hiding secrets, John decides he’ll do a security check of her store and apartment, give her some preventative tips and turn the case over to someone else. Even as the attraction between Julia and John heats up, the stalker’s letters and movements become increasingly bold.

A Whisper in the Dark is a tense thriller. Ms. Castillo keeps the reader guessing until the very end as to who the criminal really is. Julia is a little too good and John a little too bad, but since they are the main characters, they tend to balance each other for a pleasing whole.