Ruling Passion by Reginald Hill

From Yorkshire to the sleepy village of Thornton Lacey is only a morning's drive, but for Detective-Sergeant Peter Pascoe, the distance will close off part of his life forever. Motoring down for a reunion with old friends, he arrives to find not a welcome but a grisly triple murder. Out of his jurisdiction, Pascoe is in an untenable position: one of his oldest friends is wanted for murder, his boss is ordering him back to Yorkshire, and his instincts are telling him that the local constabulary will never suspect that the crime's true motive lies not in the obvious places...but in the unexplored zones of passion within a twisted heart.