Not for the weak of heart or stomach. Dave Cullen spent ten years throughly investigating the massacre at Columbine High School. His book dispels many rumors of that day (for example, the story that one victim was asked if she believed in God, answered yes, and was shot) and provides lots of details compiled from reports, autopsies, etc.

Many people won't read this because of the difficult nature of the material (both the shooters' autopsies appear in the book in graphic detail, for example). But if you're able to stomach it, this book is compelling and well worth your time.