The 1st half is how the CIA tracked and possibly protected 2 of the 9/11 hijackers from being found out and interrogated by the FBI. The 2nd half details the CIA's possible plot to recruit the hijackers all while circumnavigating the FBI.
The story details the creation and ultimate corruption of the 9/11 Commission, the Bush administration's role in orchestrating and doctoring the report, and the scandals that followed.
It focuses on just how much the top brass knew about attacks being planned by Al Qaeda and how often nothing was done or plans to do something were stopped altogether. There's also a portion about 90's Middle Eastern history and politics.
It goes over the mysterious collapse of Building 7, the Wall Street investors that got rich off the murder of 3,000 people, what foreign governments knew and neglected to tell the US, and Israeli spies. It delves deep into the conspiracy.
It focuses on how the Patriot Act stripped our government of its checks and balances, the expansion of the CIA into military matters and everywhere else in American life, and the creation of Guantanamo Bay and the torture program.