The base chief is a covert employee of the CIA; her identity is protected by law. I'll call her Kathy. She was 45 years old and a divorced mother of three. She'd spent the vast majority of her career at a desk in Northern Virginia, where she studied Al Qaeda for more than a decade. Michael Scheuer, her first boss in Alec Station, the CIA unit that tracked bin Laden, told me she had attended the operative's basic training course at the Farm, the agency's training facility, and that he considered her a good, smart officer. Another officer who knew her told me that despite her training at the Farm, she was always slotted to be a reports officer, someone who edits reports coming in from the field. She was never intended to meet and debrief informants.

Kathy knew that there was a time when only seasoned field operatives were put in charge of places like Khost. Not only would an operative need to have distinguished himself at the Farm; he would've run informants in the field for five years or more before earning such a post. He probably would have done at least one previous tour in a war zone, too. And he would have known the local language, in this case Pashto. Kathy skipped all of this. Imagine a Marine going straight from Parris Island to taking command of a combat battalion in the middle of a war.

In the late '90s, when Kathy was first put on the bin Laden account, it was the Siberia of the CIA, located in a bleak office building in Tysons Corner, Virginia. If you needed someone important to pay attention to you, you had to drive down Route 123 to the main building in Langley. And even then you'd be lucky to get fifteen minutes of anyone's time.

Truth is that until September 11, not everyone in the agency was all that worried about bin Laden. The spoiled son of a Saudi construction magnate, he hadn't done any real fighting in the Afghan war. Yes, he'd been behind a truck bombing in Nairobi and Dar es Salaam in 1998. But neither truck got inside the building, and American casualties were relatively light. Was this the best bin Laden could do? To the old guard at the CIA, he looked like a wannabe, not in the same league as Hezbollah.

That all changed on September 11, of course, when every CIA station and base in the world turned their attention to "penetrating" Al Qaeda—recruiting a mole next to Osama bin Laden. In the span of a few years, the CIA's counterterrorism center went from a couple of hundred officers to 4,000. If you wanted to rise in the CIA, you needed to prove you were doing your part to get bin Laden.

As an Al Qaeda expert, Kathy did more than her part. But Khost was her first field command, her first real chance to run informants. She lived in a trailer, ate in a common mess, experienced the isolation of life behind blast walls and razor wire, surrounded by the dun countryside of eastern Afghanistan. Like every other American serving in this part of the world, trapped on base for fear of the Taliban, she must have felt like a prisoner. But from what I've be able to glean about her, this hardship would've made her all the more determined to show her bosses that she could do the job.

to understand the CIA, you need to know that from its beginning in 1947, it was divided by a class system, as rigid and acrimonious as any. Everyone in the agency, wherever he or she stood, knew about it and either benefited or suffered from it.