The final episode explores how the September 11th attack came to be. A portrait emerges of the true mastermind of the attack, Khalid Sheikh Mohammed. Part three explores his past, including time spent in the US as a college student, through interviews with friends, journalists and the agents who devoted their lives to finding him. The episode also looks at the men recruited to enact the attacks--their backgrounds, terror training, their lives in the US and their flight training. In Washington, there is a disconnect between government agencies--information withheld, missed signals, and ensuing tensions. The film also details the experience and emotion of 9/11, and how the United States and the world were changed forever.