It begins with a series of brutal killings in Sydney, all committed in the same way against similar victims. A serial killer is at work. Another series, different victims, different "modus operandi" occurs in North Sydney, then a third is discovered in Melbourne. The Sydney Homicide Squad is baffled and frustrated as the killings continue with not a single clue being discovered to indicate the killers. Finally, the Squad leader, Detective Inspector David Hunter is able to bring his old friend and colleague out of retirement to work with him. Jack Savage, the best criminal profiler in the country had retreated to grow alpaca and grandchildren in his rural property, but when David's sister is the next victim of one of the killers, he comes down to Sydney. It gets worse. David discovers that similar serial killings are occurring in Canada, the USA, the UK and Europe, possibly more. And then he gets the break that tells him what's going on. The only way he can get to the heart of this horror is to go undercover and begin a deadly game, not knowing if he is hunter or prey or whether he will live to see the next day.