On New Year's Day, a wealthy family is found slaughtered inside their exclusive gated community in north London, their youngest child stolen away. The murder weapon is a gun for stunning cattle, leading Detective Max Wolfe to a dusty corner of Scotland Yard's Black Museum devoted to a killer who thirty years ago was known as the Slaughter Man. But the Slaughter Man is now old and dying.
"My dad used to say to me, 'Try to keep a cool head and a warm heart.' At least I think it was my dad. I don't really remember him." Gravy worked in the graveyard - hence the name. He was having a normal day until his friend Benjy turned up in a car Gravy didn't recognise. Benjy had a bullet hole in his chest, but lived just long enough to ask Gravy to hide him and look after his gun. Gravy had looked after things for Benjy before, but never a gun. When Gravy looked in the car...