Someone is blackmailing a local supermarket chain. And getting away with it, thanks to a very clever payoff method involving hole-in-the-wall bank machines and a bit of glaring police incompetence. When the blackmailers descend on Eddathorpe, Robert Graham is called in. He thinks it's an inside job - and sets out to prove it. He doesn't know the case is going to escalate from fraud to murder; or that its unravelling could change his life...