So I generally reserve 5 star reviews for a both that was both excellent *and* I'm likely to want to reread. In this case, it's not necessarily that I'm likely to pull this down off the shelf over and over again, but that it was a truly remarkable book.
Told in 17 points of view, this is the story of - or maybe it's more accurate to say "around" - a high school shooting. Each segment was written by a different YA author and is from a different character or object POV. Remarkably, it still feels like a consistent, singular work. I would have thought the tonal shifts would be too jarring, or the way it doesn't come back around in a classic narrative structure would be more like reading a series of news accounts or a short story anthology. But - and this feels like a super weird comment to make - it reads really well. It's fast, engaging, even entertaining or enjoyable, at some level. The characters are well fleshed out, though it's hard to keep track of them and their relationships to one another, especially at first. There's insight, but not explanations.
The book as a whole doesn't answer much. The shooter was a boy with some problems. He might have been a good friend. He might have been destructive from a young age. He might have been bullied. He might have been suicidal. He might have had psychological issues. It might have been the system, or isolation; other kids, or school or genetics. There's complexity and confusion and bad choices and too much unexplored desire and it pretty much captures adolescence and the terrors and triumphs of high school. It's a mess and it's brilliant and remarkable.