Two hours after the bomb explodes in Oslo, Adrian Pracon hears two sharp bangs, like a hammer striking metal. The noises come from the lawn down the hill, between the main white building and the jetty where the ferry docks.

The island, named Utoeya, pokes out of a glacial lake called Tyrifjorden twenty-five miles west of Oslo. It slopes up steeply from the jetty, and Adrian is at the top of the hill, near the cafeteria. He is 21, though it's only his first year at the summer camp for young liberals. Already he is charmed, almost smitten, by the place. _This, _he thought after he arrived on a clear Norwegian day, really is a piece of heaven on earth.

There are three more bangs. Adrian sees six or seven people—he's not counting—sprinting up the slope toward him. "Run," they're screaming. "He's shooting! Run!"

Another three bangs. But Adrian does not run. He does not recognize the noises as gunfire, and the words being screamed are so implausible as to be fantasy. People simply do not shoot one another in Norway. Adrian is not so much afraid as curious.

He hears more bangs. Two people at the top of the slope fall, abruptly and awkwardly, in midstride. Adrian steps off the main path, out of the way of the others charging up the hill. But still he does not run. He wonders if he is witnessing an elaborate ercise, if perhaps the organizers are trying to show hundreds of young campers what it would be like to live in a war zone.

A blond man in a black outfit is climbing the hill. He is not hurrying. At the top of the hill, he turns left, toward the field where the kids have staked their tents. Last night, when low clouds curtained the moon and stars, those tents glowed red and blue and yellow from the lamps lit inside, and Adrian marveled at how pretty they were. Like Chinese lanterns, he thought. Now he's stepping around them, walking backward parallel to and ten meters off of the path. The man appears to be dressed in a police commando's uniform: black trousers over what seems to be a black wet suit, a vest with many stuffed pockets and the word politi on the right breast, a backpack. He also is carrying two guns—a rifle with an elaborate sight and a bayonet affid to the muzzle and, in his right hand, a pistol. Adrian stoops into a half-crouch. He now suspects that he should, in fact, be afraid. But why would a policeman shoot people? This must be a prank, he tells himself.

He senses other kids around him, also moving in a slow half-crouch. In the middle distance, he sees a girl coming out of the showers. She's wearing gray sweatpants and a gray sweatshirt with auf stenciled on it. Apparently she did not hear the bangs or the screaming while she was in the showers, because she is walking calmly along the path toward the man with the guns.

The distance between them closes. She is only a few feet from the man when she stops, tenses. It looks to Adrian like she senses something is wrong, like she wants to run.

The man raises his right hand. He shoots her in the head.

The girl crumples to the ground.

Adrian thinks it looks nothing like it does when someone gets shot in the movies.

The man stands over her, fires once more. Her body jerks.

Adrian runs.

Seven hours before the shooting begins on 22 July, Gro Harlem Brundtland makes the short ferry crossing from the shore to Utoeya. She was Norway's first female prime minister and is affectionately known as "the Mother of Norway." She is scheduled to stay through dinner at the camp.

The Labor Party Youth League (Arbeidernes Ungdomsfylking in Norwegian, abbreviated to AUF) has held a camp on Utoeya every summer for sixty-one years. The AUF is by far the largest political youth organization in Norway, and its parent party, Labor, has long been the dominant faction in a coalition government. The island itself, which is small and heart-shaped, was a gift to the AUF from the Oslo and Akershus trade unions in 1950. There are a few buildings—the main white building, the cafeteria, a cherry red schoolhouse, tiny green cabins—and a soccer pitch in a clearing, but most of Utoeya is forest and meadow. A narrow path follows the edge of the island as it rises to cliffs on the western side, then back down to a rocky beach on the southern tip. It has been known for generations as Kjærlighetsstien, the Lovers' Trail.