Soul Music: Book 3 in the Death arc.
Death - Exploring the afterlife with DEATH himself... and his skeletal horse Binky... and his daughter. If mass extinction, end of world scenario’s and anthropomorphic personifications tackling human emotions sounds like your thing look no further.
This is a story about sex and drugs and Music With Rocks In.
…one out of three ain’t bad.
Being sixteen is always difficult, even more so when there’s a Death in the family. After all, it's hard to grow up normally when Grandfather rides a white horse and wields a scythe. Especially if he decides to take a well-earned moment to uncover the meaning of life and discover himself in the process, so that you have to take over the family business, and everyone mistakes you for the Tooth Fairy.
And especially when you have to face the new and addictive music that has entered Discworld. It's lawless. It changes people. It's got a beat and you can dance to it.
It's called Music With Rocks In.
And it won't fade away.
A young harpist, Imp Y Celyn from Llamedos (spelled backwards, "sod 'em all," a tribute to LLareggub in Welsh poet Dylan Thomas' Under Milk Wood), comes to Ankh-Morpork in hopes of becoming famous. Unable to afford the Musicians Guild fees, he and fellow unlicensed musicians Lias Bluestone (a troll percussionist) and Glod Glodsson (a dwarf hornblower) form "The Band with Rocks In," named after Lias' tuned rocks. When Imp's harp is destroyed, he acquires a guitar from a mysterious shop, unaware that it contains the awareness of a primordial music that was responsible for bringing the universe into existence. Imp takes the new name "Buddy," as "Imp Y Celyn" literally means "bud of holly," and Lias starts calling himself "Cliff."
Meanwhile, Death is upset over the deaths of his adopted daughter Ysabell and her husband, his former apprentice Mort. Their daughter, Susan Sto Helit, was initially raised with an awareness of Death as her grandfather, but they later withheld the truth from her and she forgot about it. She attends boarding school in Quirm, and is content to avoid unpleasant conversations by using her unexplained ability to fade from others' awareness. When Death abandons his post, going on an impromptu sabbatical in an effort to forget the painful memories, the fabric of reality forces Susan to take on his duties and she begins to remember her past. She becomes aware of Buddy when he is scheduled to die in a riot while performing at the Mended Drum, but instead the crowd is overcome by the spirit of "Music with Rocks In," which apparently has no musical merit for objective listeners not themselves possessed by it. After this, Buddy's life is powered by the music instead of by his natural life force.
Cut-Me-Own-Throat Dibbler becomes the Band's manager. He hires the troll Asphalt as a roadie to accompany the band on its tour as he books them to play to increasingly large crowds throughout the city and the region, all the while keeping them unaware of the large profits he is earning. Buddy is becoming less and less like himself, and barely seems aware of his surroundings when he is not playing the guitar. Susan tries to protect him from the influence of the music; though she does not acknowledge it, she has developed feelings for him. Meanwhile, the music is affecting many of the people who have heard it, causing them to form their own bands and adopt behaviors associated with the fans of various musical movements on 20th Century Earth. The wizards of Unseen University are particularly affected by this phenomenon, though not Archchancellor Ridcully, who uses the newly invented device Hex and works with Susan in an effort to understand these events. And Mr. Clete, the murderous secretary of the Musicians Guild, becomes increasingly unhinged by his inability to stop the Band's unauthorized activities (as they are protected by the music).
Buddy wants to perform a free concert at the music's behest, and Dibbler agrees after realizing how much of a profit he can earn through merchandising and concessions. A large number of the copycat bands participate in the largest concert of all time, culminating in the Band with Rocks In's performance. Buddy also performs his own folk song on his harp, which Glod has had repaired, which briefly restores Imp's natural personality and grants him a moment of peace. Afterwards, the band flees from their crazed fans, pursued by the Musicians Guild, Dibbler, Susan, and Death (who has been brought back to his senses by his servant Albert). The music intends to create an immortal legend by crashing the band's coach into a gorge, with no survivors. Susan rescues them, but the music begins to alter the timeline so the band will have died. Death then arrives, playing an "empty chord" on the guitar to stop the music, having Buddy play a chord to restart it, and then destroying the guitar.
A new timeline is created in which Mr. Clete was the only fatality, although Susan remains aware of the original course of events. She is returned to school (and also has been there all along) with a new self-assurance. The next day, she runs to reunite with Imp upon realizing that, in the new version of events, he came to Quirm instead of Ankh-Morpork and is working nearby.