Alan Gregory is reunited with the woman he once loved when they are brought in to catch an evil mass murderer who has already killed five people and now wants to make them his next victims.

Charlie has reluctantly returned to her childhood home of Boulder, Colorado to be with her mother who just had major surgery. Boulder evokes decidedly mixed feelings in Charlie. She left after her daughter Libby was conceived 16 years ago, and hasn't returned until now. There's plenty to keep her emotions occupied, though, since her mother seems to be suspected of doing away with one of her neighbors. Charlie has lots to ponder, including: What happened...