One rainy March evening, an anti-nuclear demonstration outside the Eastvale Community Centre turns nasty: the mood of the crowd begins to darken as the weather worsens. Finally the police lose control and violence erupts, leaving one policeman dead with almost a hundred suspects.

Detective Chief Inspector Banks is back, investigating his third case in Yorkshire. But things become difficult for him when Superintendent Richard “Dirty Dick” Burgess is sent from London, for political reasons, to lead the investigation. Sifting through a host of unusual suspects and disturbing discoveries about the police themselves, Banks is warned off the case. But the only way he can salvage his career is by beating Burgess to the killer. As the two head for a final confrontation, Banks pieces together the full story behind his most tragic case so far.