In the words of the commission’s co-chairmen, this is the compelling inside story of how the National Commission on Terrorist Attacks Upon the United States—more commonly known as the 9/11 Commission—managed to succeed against all odds in producing a report that made clear what went wrong and why.

The mandate of the 9/11 Commission was daunting and all-encompassing. In its investigation of the events leading up to and including September 11, 2001, the commission had to examine U.S. diplomacy, military policy, intelligence agencies, law enforcement, border and aviation security, and congressional oversight, as well as the immediate response to the terrorist attacks, while also investigating the lethal enemy al Qaeda.

The creation of the 9/11 Commission was blocked for months by the Bush administration, and after its inception in December 2002 the commission spent months mired in a series of controversies—the resignation of its first chairman, Henry Kissinger, and vice-chairman, George Mitchell; an inadequate budget; an extraordinarily polarized atmosphere leading up to the 2004 presidential election; the conflicting demands of various interest groups; the distrust of the victims’ families; difficulties in obtaining access to highly classified documents and to al Qaeda detainees; and a media eager to record stumbles and gaffes.

The obstacles were great, and the expectations for a blue-ribbon panel are never high—yet somehow the 9/11 Commission overcame everything that might have thwarted it and succeeded beyond anyone’s greatest expectation, holding a series of hearings that riveted the nation, producing a unanimous and widely heralded report that became a national best seller, and issuing recommendations that led to the most significant reform of America’s national security agencies in decades.

The 9/11 Commission report slaked the national thirst for accountability. Here for the first time is the story of how the commission came together to produce its landmark document.