A portrait of Khalid Sheikh Mohammed, the mastermind of the Sept. 11 attacks. A look at the men recruited to carry out the attacks, including their backgrounds and training. An examination of missed signals in Washington, D.C., prior to the attacks.

Clinton administration officials react to the rise in jihadi terror. Operations are planned targeting Osama bin Laden resulting in near misses. A profile of bin Laden emerges through interview footage with him and commentary from people who knew him.

While investigating the assassination of a rabbi in 1990, agents discover a Brooklyn-based terrorist cell with connections to Osama bin Laden. In 1993, cell members succeed in setting off a bomb in the World Trade Center, killing six people.