A mutilated body found at a rock festival. In spite of dire predictions, the rock festival in Kingsmarkham seemed to be going off without a hitch, until the hideously disfigured body is discovered in a nearby quarry. And soon Wexford is investigating the links between a local girl gone bad and a charismatic singer who inspires an unwholesome devotion in his followers. Some Lie and Some Die is a devilishly absorbing novel, in which Wexford's deductive powers come up against the aloof arrogance of pop stardom.   With her Inspector Wexford novels, Ruth Rendell, winner of the Mystery Writers of America Grand Master Award, has added layers of depth, realism and unease to the classic English mystery. For the canny, tireless, and unflappable policeman is an unblinking observer of human nature, whose study has taught him that under certain circumstances the most unlikely people are capable of the most appalling crimes.