The story is fact-based fiction. It is the story of a high school shooting. It is not a story of how 'bad' guns are. In fact, it is very balanced and little is said about the use of firearms.
Yes, it is a work of fiction. Yet it is so true. The human spirit is fragile and many go through life, parents, educators, students, children, people...intentionally, unintentionally, with and without malice, innocently and not so innocently, crushing that delicate spirit.
It is the most difficult, yet most important book I have ever read. I urge you to read it NOW.