A Savage State of Grace — Donald MacKenzie

When ex-Detective Inspector John Raven goes on jury duty, the trial he attends is the prosecution of an Englishman and his German girlfriend for heroin smuggling. Raven is convinced the girl has been duped, but she is sentenced while Pelham, her 'lover' goes free. When the girl commits suicide in jail, Raven is determined to expose the truth. Following the trail of her missing diary and using Pelham as a stalking-horse, Raven unravels a ruthless international conspiracy.