There are 15 horrific deaths in Messiah - but of those it is the four murders in the past that set off a chain of terrifying killings that pose a seemingly impenetrable problem for Red and his team.
Four convicted men are safely behind bars for those murders. Yet someone, somewhere believes they are innocent. Which can only mean that the real murderers are still out there and justice - brutal, bloody and painstakingly planned - is being meted out by a sadistic serial killer.
Could the police have made mistakes that resulted in the wrong men being imprisoned? Or has there been a cover-up to hide the shocking truth - that evidence has been withheld, or tampered with to obtain unsafe convictions?
The horrifying truth dawns as the body count rises. The killer is out for revenge - and none of the investigating teams, or their nearest and dearest, is safe...