Soul Music (Discworld Novel)

Death goes walk-about and tries everything, including joining the French Foreign Legion, to forget a tragic carriage accident at dead man's curve. His independent-minded teen granddaughter has to surreptitiously take over the reaping biz. Three guys invent music with rocks in it or did the magick in this music invent them? Is time changing or - déjà vu all over again- is it rushing to a new tragedy on Dead Man's Curve?