Former New York Times reporter Kurt Eichenwald is a master at making complicated stories easily understood. In the past, he has focused on business, notably the implosion of Enron and price-fixing at Archer Daniels Midland. In his latest effort he turns his attention to the Bush administration’s War on Terror and the decisions its officials made in the course of 18 months that changed the world.

500 Days opens at the Bush ranch in Crawford, Tex., more than a year before the 9/11 attacks. Gov. George W. Bush had just won the Republican nomination for president, and a lineup of experts began making a pilgrimage to Crawford to brief him.

The then-deputy director of the CIA’s Counterterrorism Center, Ben Bonk, arrived with a ruse in mind. Because of Bush’s reputation for folksiness, Bonk decided to provide him with a vivid example of the terrorist threat. He had smuggled a fake briefcase bomb into the briefing room; and while he had let the Secret Service in on what he was doing, the future president had been left in the dark. The briefcase contained no poison gas, but the device was real enough. It was based on a briefcase designed by a Japanese cult that had released poison gas on the Tokyo subway in 1998.

When Bonk’s turn to speak came, he began laying out the dangers of Islamic fundamentalism. He singled out al-Qaeda in particular, saying it was the group most likely to succeed in getting chemical, biological, radiological or nuclear weapons. These weapons of mass destruction didn’t have to be large or cumbersome to transport, he told the future president.

Then he “reached for his briefcase, stood, and walked toward Bush. As he approached, Bonk popped it open and tilted the case forward. Bush saw the red digits counting down. ‘Don’t worry,’ Bonk said. ‘This is harmless. But it is exactly the kind of chemical device that people can bring into a room and kill everybody.’ He glanced down at the timer. ‘And this one would be going off in two minutes.’ Bush looked at his senior adviser Josh Bolten. ‘You got one and a half minutes to get that thing out of here,’ he said.”

And so begins Eichenwald’s latest epic addition to what has become a crowded field: terrorism narrative nonfiction. 500 Days is based on the idea that almost every aspect of Bush’s so-called War on Terror — from Afghanistan and Iraq to warrantless wiretapping, rendition and the torture of prisoners — grew out of a series of decisions made in the first 500 days after the 9/11 attacks. Eichenwald meticulously dissects almost every one.

Although much of what Eichenwald covers is familiar ground, he has managed to produce a page-turner because of his journalistic attention to detail. Readers are given fly-on-the-wall details as Bush administration officials weigh life-and-death decisions. In some cases, there are jaw-dropping illustrations of executive overreach — including new details about the warrantless wiretapping program — and in others, the book depicts a seemingly cavalier disregard for the consequences of decisions. (In a discussion about torture, a CIA lawyer says, “It basically is a matter of perception. If the detainee dies, you’re doing it wrong.”)

Eichenwald uses the literary equivalent of direct cinema to tell his story. The chapters are set up as a series of ever-changing vignettes: Readers are in the White House dining room one moment and then taken to a Long Island church and soon to the hills of Afghanistan in the space of a few pages. Most of the time, the literary device works, but I found myself wondering if someone less steeped in the names and places that Eichenwald includes might feel a bit whipsawed — or worse, a bit lost.