Book excerpt: Ruth Munro, the glamorous wife of a successful author, brutally stabs a man in a flat in Edinburgh's red light district in a seemingly unprovoked attack, leaving him for dead. When the case is investigated it reveals dark secrets from Ruth's past-a past of which Paul, her husband, was blissfully unaware. As Paul struggles to come to terms with the grim reality of his wife's former life, her lawyer tries to piece together enough of Ruth's story to build a defence against an apparently watertight case. Meanwhile a dark angel is rising, gathering strength to deliver his final twisted message. A tale of blackmail, prostitution, murder and revenge, Rod MacDonald's compelling first novel carries on the great tradition of Edinburgh crime thrillers.