A second mass murder occurs with no signs of an obvious break-in and no forensic evidence for Chandler and the team to use. The crimes begin to take on an almost supernatural edge and local residents wonder how they can sleep soundly in their beds when doors and locks offer no protection from whoever is responsible.

When traces of the aphrodisiac Spanish fly are found in murder victims, Chandler and Miles question what kind of killer they could be up against. The team are taken to the heart of a dark obsession where romance and love take on a sinister turn.