DS Lasser knows time is running out, two women assaulted within the space of a week and now the 'crazy' is carrying a knife.
When Sarah Palmer is attacked on her way home from a night on the tiles, she knows she is seconds away from death. She can feel the cold sliver of the blade at her throat; his hot sour breath on her neck as he whispers his vicious promises. So, when a passing stranger appears out of the drizzle mist to save her, Sarah feels a cataclysmic sense of relief that soon turns to despair as she realises her saviour has vanished into the downpour.
All his life Robert Flynn has heard voices in his head, his mother used to call them his imaginary friends, that was until the man with the bright smile opened her throat with the shiny blade. Now, he can hear only one and it's telling him to do things that make him feel bad. Trouble is, without his medication he becomes confused and the voice inside will only allow him sanctuary if he does exactly as he's told.
As Sarah becomes more and more obsessed with finding the man who came to her aid, she leads them all into danger when she decides to take drastic measures that rebound with horrific consequences.
As Lasser's worst fears are brought to life, he finds himself hunting a man who appears to have no moral compass, but when the true nature of the killer is revealed, Lasser realises that someone else laid the seeds that grew and festered, someone beyond reproach who wears a bright smile to cover his identity.
As the killer runs amok, Lasser must try to second-guess his intentions before more innocents are killed. Though he soon comes to realise it's not only the police hunting the killer, someone else has a stake in putting an end to his reign of terror.