Corrupt copper and bad Catholic Jimmy Costello is back, and he's studying to be a priest in Rome. But his old life refuses to stay buried... When a visiting archbishop dies in suspicious circumstances, the Kilburn hard man is asked to drop his religious studies and help local police investigate. Together with his partner Inspector Ricci, Jimmy follows a twisting trail of evidence from the streets of the Holy City to Glasgow and back, where they uncover a sinister plot more evil than they had ever imagined.