Peter Diamond, head of the Criminal Investigation Division in scenic Bath, England, is investigating the murder of a young woman whose body has been found in the canal, the only clue to her identity a taboo of a music note on one of her teeth. Meanwhile, jobbing violist Mel Farran strangely finds himself scouted by a very elite classical quartet -- one whose previous violist disappeared without a trace. For Diamond, who wouldn't know a Stradivarius from a French horn, the investigation is his most demanding ever.