The Singing Sands — Josephine Tey

The young man with the tumbled black hair and the reckless eyebrows was dead in compartment B Seven on the night train from London. The only message he had left behind was a verse--a strange unfinished poem that haunted Inspector Grant--that spoke of talking beasts and singing sands guarding the way to Paradise. Even on sick leave in Scotland, Grant couldn't let the puzzle alone or relax and enjoy the heather until he had uncovered all the details in one of the cleverest murders in criminal history.