On April 20, 1999, Dylan Klebold and Eric Harris, two seniors at Columbine High School in Littleton, Colorado, walked into their school and shot to death twelve students and one teacher, and wounded many others. It was the worst single act of murder at a school in U.S. history. Few people knew Dylan Klebold or Eric Harris better than Brooks Brown. Brown and Klebold were best friends in grade school, and years later, at Columbine, Brown was privy to some of Harris and Klebold's darkest fantasies and most troubling revelations. After the shootings, Brown was even accused by the police of having been in on the massacre―simply because he had been friends with the killers. Now, for the first time, Brown, with journalist Rob Merritt, gets to tell his full version of the story.