It is 1921 and young constable Billy Styles is about to experience a horrifying awakening to life as a police officer. For a dreadful discovery has been made at a monor house deep in the Surrey countryside-the bloodied bodies of Colonel Fletcher, his wife Lucy and two of their staff. They have all been stabbed to death-and the lack of disturbance in the house suggests the attack was one of terrifying speed.

The Surrey police force seem sure the murders are simply the result of robbery with violence, but Billy's superior, Detective Inspector John Madden, brought in from Scotland Yard, sees matters very differently.

For Madden has experienced the horrors of the Great War and has seen madness at first hand. And this crime, he is sure, has been perpetrated by a psychopath who will strike again...and soon.