I really enjoyed reading this, but it's a somewhat overwhelming experience. It's structurally a detective story, but there's a lot more going on. Technically, you could call it a supernatural investigation—our protagonist has unnaturally acute hearing and the plot centers on a group of children with supernatural abilities—but whatever you're thinking, it's not that. There are conventions around that kind of story, and this doesn't fit. It's weirder.

The story jumps around a lot, chronologically: flashbacks inside flashbacks. There are a lot of characters, and they tend to show up unexpectedly in different contexts. Initially, it's not at all clear what's really going on, who is involved, and what the motivations and alliances are. I enjoy that, but be ready for it. It's one of those stories you kinda need to read twice (which I haven't yet): first to get an overall sense of what is happening, and then to go through and take notes on who knows what when.

It would also be helpful to have an understanding of music theory and a familiarity with classical music (neither of which I have) because that's how Kasper, our protagonist, perceives the world, in a literal way.