One of Us:The Story of Anders Breivik and the Massacre in Norwayby Asne SeierstadFarrar, Straus and Giroux, 2015Norwegian journalist Asne Seierstad, the author of the bestselling The Bookseller of Kabul, takes for her new book One of Us a subject terrifyingly closer to home: the 2011 Oslo massacre that left 77 people – many of them teenagers – dead at the hands of a single gun- and bomb-wielding assailant. On 22 July 2011, a man named Anders Behring Breivik detonated a bomb outside the Oslo office of Norway's prime minister, killing eight people. He then killed 69 people at a youth camp on the island of Utoya. Most of the Utoya victims were the young members of the country's Labour Party, and it quickly became evident that Breivik had been acting at least in part for political reasons; he'd allied himself with right-wing extremist groups and filled his imagination with a toxic stew of social and xenophobic rantings, many of which later found their way into a manifesto with eerily prescient passages:

“Once you decide to strike, it is better to kill too many than not enough, or you risk reducing the desired ideological impact of the strike. Explain what you have done (in an announcement distributed prior to the operation) and make certain that everyone understands that we, the free peoples of Europe, are going to strike again and again.”

After slaughtering island visitors for an hour (including shooting people who were attempting to swim to safety), Breivik surrendered to police and later stood trial in the most jarring public spectacle Norway had seen in centuries. He was convicted and sentenced to 21 years in prison, although that sentence can and almost certainly will be extended indefinitely, since its completion requires that Breivik be judged as no longer a threat to society.In order to write what will surely be the definitive account of the tragedy, Seierstad has worked for years doing extensive interviews with everybody involved, and as a result, One of Us is both more ample and far more involving than a typical what-happened-next expose would have been. Through lavish detail and a dramatic (only very occasionally verging on the melodramatic) narrative style, she takes readers deep into the worlds of all the victims and deeper – almost unbearably so – into the world of the killer, following him in elaborate detail through the many twists and turns of his years' worth of preparation – and into his thinking as he prepared:

His activities at Valstua were extremely hazardous. The barn was full of chemicals, the liquids were unstable and his working process was experimental. He had scarcely any safety measures. Sometimes he freaked out when he read about security precautions and all the eventualities that could lead to explosions. Contact with air was dangerous; contact with metal, concrete and plastic could increase static electricity and cause a detonation. So could friction and impact, an proximity to petrol, diesel and electric sockets. He was scared of what would happen to him if the explosive material went off. The blast wave/flame would probably cauterise my wounds, resulting in an extended and extremely painful death.' He made sure to keep the Glock to hand in his working area, so if he survived an explosion but lost his arms he could still shoot himself in the head by pulling the trigger with his toes.

The strange and vaguely sickening thing that emerged about Breivik during his trial – and that emerges from One of Us with renewed though unwanted force – is that whatever else this man might have been, he wasn't insane in any sense of the word we normally use. He was intelligent, well-educated, articulate, compassionate toward his friends, caring in his relationships – and he was volubly outraged during his trial at any insinuations to the contrary. He planned for years the slaughter he eventually carried out, and he believed it was the right thing to do (“the desired ideological impact of the strike”), and he knew the whole time that his social and political views were considered volatile and extreme by the majority of his friends, acquaintances, and countrymen, but he was committed to his cause. At his trial, he scorned the very idea that he could be reduced to a mere madman, and his prosecutors could find almost no evidence of mere madness in his personal history – except for the fact that he cold-bloodedly murdered 77 people and wounded hundreds more. It adds an utterly chilling dimension to the title of this shatteringly sad book.