Tucked in a piney notch in the gentle folds of the Adirondacks' southern skirts—just up from a derelict Mohawk, Adirondack & Northern rail spur—is a 22-year-old aluminum bunker tricked out with antennae tilted skyward. It could pass for the Jetsons' garage or, in the estimation of one of the higher-ranking U.S. Air Force officers stationed there, a big, sideways, half-buried beer keg.

As Major Kevin Nasypany, the facility's mission-crew commander, drove up the hill to work on the morning of 9/11, he was dressed in his flight suit and prepared for battle. Not a real one. The Northeast Air Defense Sector (neads), where Nasypany had been stationed since 1994, is the regional headquarters for the North American Aerospace Defense Command (norad), the Cold War–era military organization charged with protecting North American airspace. As he poured his first coffee on that sunny September morning, the odds that he would have to defend against Russian "Bear Bombers," one of norad's traditional simulated missions, were slim. Rather, Nasypany (pronounced Nah-sip-a-nee), an amiable commander with a thick mini-mustache and a hockey player's build, was headed in early to get ready for the norad-wide training exercise he'd helped design. The battle commander, Colonel Bob Marr, had promised to bring in fritters.

neads is a desolate place, the sole orphan left behind after the dismantling of what was once one of the country's busiest bomber bases—Griffiss Air Force Base, in Rome, New York, which was otherwise mothballed in the mid-90s. neads's mission remained in place and continues today: its officers, air-traffic controllers, and air-surveillance and communications technicians—mostly American, with a handful of Canadian troops—are responsible for protecting a half-million-square-mile chunk of American airspace stretching from the East Coast to Tennessee, up through the Dakotas to the Canadian border, including Boston, New York, Washington, D.C., and Chicago.

It was into this airspace that violence descended on 9/11, and from the neads operations floor that what turned out to be the sum total of America's military response during those critical 100-some minutes of the attack—scrambling four armed fighter jets and one unarmed training plane—emanated.

The story of what happened in that room, and when, has never been fully told, but is arguably more important in terms of understanding America's military capabilities that day than anything happening simultaneously on Air Force One or in the Pentagon, the White House, or norad's impregnable headquarters, deep within Cheyenne Mountain, in Colorado. It's a story that was intentionally obscured, some members of the 9/11 commission believe, by military higher-ups and members of the Bush administration who spoke to the press, and later the commission itself, in order to downplay the extent of the confusion and miscommunication flying through the ranks of the government.

The truth, however, is all on tape.

Through the heat of the attack the wheels of what were, perhaps, some of the more modern pieces of equipment in the room—four Dictaphone multi-channel reel-to-reel tape recorders mounted on a rack in a corner of the operations floor—spun impassively, recording every radio channel, with time stamps.

The recordings are fascinating and chilling. A mix of staccato bursts of military code; urgent, overlapping voices; the tense crackle of radio traffic from fighter pilots in the air; commanders' orders piercing through a mounting din; and candid moments of emotion as the breadth of the attacks becomes clearer.

For the neads crew, 9/11 was not a story of four hijacked airplanes, but one of a heated chase after more than a dozen potential hijackings—some real, some phantom—that emerged from the turbulence of misinformation that spiked in the first 100 minutes of the attack and continued well into the afternoon and evening. At one point, in the span of a single mad minute, one hears Nasypany struggling to parse reports of four separate hijackings at once. What emerges from the barrage of what Nasypany dubs "bad poop" flying at his troops from all directions is a picture of remarkable composure. Snap decisions more often than not turn out to be the right ones as commanders kick-start the dormant military machine. It is the fog and friction of war live—the authentic military history of 9/11.