Columbine is a non-fiction book written by Dave Cullen and published by Twelve (Hachette Book Group) on April 6, 2009. It is an examination of the Columbine High School massacre, on April 20, 1999, and the perpetrators Eric Harris and Dylan Klebold. The book covers two major storylines: the killer's evolution leading up to the attack, and the survivors' struggles with the aftermath over the next decade. Chapters alternate between the two stories. Graphic depictions of parts of the attack are included, in addition to the actual names of friends and family (the only exception being the pseudonym "Harriet", which is used for a female Columbine student referred to in Klebold’s journal entries, with whom he was obsessively in love).