READ EXCERPT: 'Columbine'

June 18, 2009— -- "Good Morning America" gave you a glimpse at some of O Magazine's top summer reading selections today.

It's been a decade since the shocking school massacre at a Colorado high school stunned the nation, and journalist Dave Cullen's book, "Columbine," offers vivid details about one of the most disturbing days in the nation's history.

The book's narrative also does some myth-busting and suggests the killers weren't social outcasts; there was no broader conspiracy and authorities should have known.

Read an excerpt of this book below and check out other books on the list.

Click here to read an excerpt from "Pride and Prejudice and Zombies."

Click here to read an excerpt from "Stormy Weather."

Click here to read an excerpt from "Provenance."

PART I

1.Mr. D

He told them he loved them. Each and every one of them. He spoke without notes but chose his words carefully. Frank DeAngelis waited out the pom-pom routines, the academic awards, and the student-made videos. After an hour of revelry, the short, middle-aged man strode across the gleaming basketball court to address his student body. He took his time. He smiled as he passed the marching band, the cheerleaders, and the Rebels logo painted beneath flowing banners proclaiming recent sports victories. He faced two thousand hyped-up high school students in the wooden bleachers and they gave him their full attention. Then he told them how much they meant to him. How his heart would break to lose just one of them.

It was a peculiar sentiment for an administrator to express to an assembly of teenagers. But Frank DeAngelis had been a coach longer than a principal, and he earnestly believed in motivation by candor. He had coached football and baseball for sixteen years, but he looked like a wrestler: compact body with the bearing of a Marine, but without the bluster. He tried to play down his coaching past, but he exuded it.

You could hear the fear in his voice. He didn't try to hide it, and he didn't try to fight back the tears that welled up in his eyes. And he got away with it. Those kids could sniff out a phony with one whiff and convey displeasure with snickers and fumbling and an audible current of unrest. But they adored Mr. D. He could say almost anything to his students, precisely because he did. He didn't hold back, he didn't sugarcoat it, and he didn't dumb it down. On Friday morning, April 16, 1999, Principal Frank DeAngelis was an utterly transparent man.

Every student in the gymnasium understood Mr. D's message. There were fewer than thirty-six hours until the junior-senior prom, meaning lots of drinking and lots of driving. Lecturing the kids would just provoke eye rolling, so instead he copped to three tragedies in his own life. His buddy from college had been killed in a motorcycle accident. "I can remember being in the waiting room, looking at his blood," he said. "So don't tell me it can't happen." He described holding his teenage daughter in his arms after her friend died in a flaming wreck. The hardest had been gathering the Columbine baseball team to tell them one of their buddies had lost control of his car. He choked up again. "I do not want to attend another memorial service."

"Look to your left," he told them. "Look to your right." He instructed them to study the smiling faces and then close their eyes and imagine one of them gone. He told them to repeat after him: "I am a valued member of Columbine High School. And I'm not in this alone." That's when he told them he loved them, as he always did.

"Open your eyes," he said. "I want to see each and every one of your bright, smiling faces again Monday morning."

He paused. "When you're thinking about doing something that could get you in trouble, remember, I care about you," he said. "I love you, but remember, I want us all together. We are one large family, we are—"

He left the phrase dangling. That was the students' signal. They leapt to their feet and yelled: "COL--um-BINE!"

Ivory Moore, a dynamo of a teacher and a crowd rouser, ran out and yelled, "We are ...""COL--um-BINE!"

It was louder now, and their fists were pumping in the air.

"We are ..."

"COL--um-BINE!"

"We are..."

"COL--um-BINE!"

Louder, faster, harder, faster -- he whipped them into a frenzy. Then he let them go.They spilled into the hallways to wrap up one last day of classes. Just a few hours until the big weekend.

All two thousand students would return safely on Monday morning, after the prom. But the following afternoon, Tuesday, April 20, 1999, twenty-four of Mr. D's kids and faculty members would be loaded into ambulances and rushed to hospitals. Thirteen bodies would remain in the building and two more on the grounds. It would be the worst school shooting in American history -- a characterization that would have appalled the boys just then finalizing their plans.