The Wages of Sin: Stonemason Andrew Knightley is pushed under a London Underground train during the morning rush hour. DI Max Arnold and his partner, DS Priya Shamsie, together build a picture of a lonely, devout, and troubled man who believed a spirit was leaving him vengeful Biblical messages. But the killer is flesh and blood, and a more earthly explanation may be found in the truth of Knightley's life.