Today, 10 years later, is a book about the shootings at Columbine even necessary? Surely, around-the-clock media coverage of the attack and the reverse deification of Eric Harris and Dylan Klebold (Virginia Tech shooter Seung-Hui Cho evoked their names like a St. Christopher of the School Shooter in videos before his gruesome rampage) ensures that everyone remembers what happened just over a decade ago.

Or not.

"We remember Columbine as a pair of outcast Goths from the Trench Coat Mafia snapping and tearing through their high school hunting down jocks to settle a long-running feud," Dave Cullen writes in the middle of Columbine, his comprehensive, 400-page account of the Colorado high-school shootings. "Almost none of that happened." The most surprising thing about Columbine is how many pages Cullen devotes to amending the popular misconceptions that followed the shootings.

Cullen has earned the (admittedly, not heavily contested) title of world's preeminent Columbine expert. He arrived at the school around noon on April 20, 1999, about 40 minutes after Harris and Klebold began their attack, and he has done thousands of hours of interviews with families and survivors of the shootings in the decade since.

Cullen patiently clears the record of popular myths, tracking their birth and development, like the early claim that Harris and Klebold were gay. Cullen traces that story to a television news interview with a Columbine student:

"'They're freaks,' said an angry sophomore from the soccer team. 'Nobody really liked them, just 'cause they—' he paused, then plunged ahead. 'The majority of them were gay. So everyone would make fun of them.'"

Neither of the shooters was gay—Klebold entertained an elaborate fantasy romance with a female classmate and Harris was an exceedingly confident ladies' man—but the comment was adopted as salacious fact and repeated ad nauseam almost immediately afterward. Anti-gay activists, to this day, repeat the lie in their homophobic tirades. More myths about the shooting fall away under Cullen's scrutiny: Both boys were fairly popular. The trench coats that they wore were to conceal the weapons, not to make a statement (and neither of the boys identified as goths). The assault wasn't planned for April 20 to commemorate Adolf Hitler's birthday, as urban legends have it. Instead, the shooting was supposed to fall on April 19, as a tribute to Timothy McVeigh's Oklahoma City bombing.

In fact, Cullen reports, "The boys were going to double or triple McVeigh's record." The original plan for what they referred to as "Judgment Day" or "NBK" (for "Natural Born Killers") was much more elaborate than what played out: Harris and Klebold stuffed duffel bags with bombs and shrapnel to go off in the cafeteria, to potentially kill hundreds, and would follow that with a shooting spree to kill the survivors. The boys planted bombs in their cars to blow up forty-five minutes after the assault, to kill media and first-responders who would have started moving into the crime scene. The bombs were placed, but they didn't detonate because they were improperly assembled.

After studying their journals, Cullen determined that Harris was the driving force behind Columbine. Harris's journal, which he named "The Book of God," at first resembles nothing more than the writing of an angry, melodramatic teenager: "[School] is societies way of turning all the young people into good little robots." But later, in journals and on his website, Harris listed people he wanted to kill, considering himself an agent of "Natural SELECTION!!!!!!!!!!!" Klebold wrote almost entirely about unrequited love and suicide, and Cullen suggests that he nearly blew the whistle on the plan several times.

Cullen also undertakes the precarious task of debunking the legend of Cassie Bernall, the evangelical Christian girl who was murdered by Harris supposedly because she believed in God. An account of Bernall's story, published under the title She Said Yes, made both Christian and mainstream best-seller lists. Bernall became an icon, a call to action for the burgeoning evangelical movement that, in a few months, would buoy George W. Bush to victory over John McCain in the Republican primaries. Cullen finds two eyewitnesses who have always discounted that story: "She [saw] Eric walk up with the shotgun in his right hand, slap Cassie's tabletop twice with his left, and say, 'Peekaboo.'... Cassie looked desperate, holding her hands up against the sides of her face. Eric poked the shotgun under and fired. Not a word."

Only the first third of the book is devoted to recounting the attacks. The bulk of Columbine describes the community's struggle to heal in the aftermath, under ridiculously intense media scrutiny and a serious increase in violent crime: "The new year began, and it got worse," Cullen writes. "A young boy was found dead in a Dumpster a few blocks from Columbine High. On Valentine's Day, two students were shot dead in a Subway shop two blocks from the school. The star of the basketball team committed suicide." That story is told simultaneously with chapters of Harris and Klebold's preparations for the shooting. These braided narratives, going forward and backward in time, reflect the good and the bad of suburban life: A community comes back together even as two young men plan to destroy it.

From the demonization of gays to the persecution complex of evangelicals to the fear that a mass murderer might be hiding inside every trench coat (eerily prescient of the post-9/11 fear that a terrorist might be skulking behind every Muslim beard), the story America told itself about Columbine revealed more about the country than about the shooters. With rational thought and rigorous journalism—and an investigation of how the media egregiously misinterpreted the truth—Cullen shows us why we need to be eternally vigilant. Not against something as simple and childish as a shadowy gunman; instead, we need to take care that the stories that we tell ourselves are honest and meaningful. It's a lesson we need to learn again and again. recommended