“The Ghost” is the nickname that Port Authority Detective Matthew Besheer and FBI Special Agent Frank Pellegrino give to the man they’ve been hunting for years but can’t quite catch: Khalid Sheikh Mohammed -- also known as KSM. He’s the uncle of Ramzi Yousef, and he picks up his plot to hijack planes and fly them into buildings. Without knowing his specific plans, Pellegrino and Besheer are acutely aware of the scope of KSM’s ambition, and the danger he presents to both military and civilian targets. But once again, a carefully considered plan to diffuse the threat goes awry and he melts into the ether. Soon he’ll take a meeting with Osama bin Laden and lay out the framework for what will become known as the attacks on 9/11/2001. In this final episode of the series, we trace the final steps to that fateful day.