For years, they remained nearly invisible, a small group of dedicated men waiting for the perfect chance to strike. Then, on September 11, 2001, they took action. The story behind the 9/11 hijackers' elaborate and ambitious plans come disturbingly to light. The group, now collectively known as the Hamburg Cell, was ultimately found responsible for the cultivation of the al-Qaeda plot code-named "the planes operation." From the Middle East to U.S. shores, track the progress of this unlikely group of comrades, who developed for unassuming college students into zealous religious martyrs.