S3, E12: The Middle East is fracturing. Arab uprisings and military interventions across the region have caused civil wars and spawned terrorist groups. Stuck in the middle of it all is Saudi Arabia. Confronted by extremism on all sides, the desert kingdom is building massive fences at its borders with Iraq and Yemen to keep out terrorist organizations that it may have had a hand in creating. Suroosh Alvi travels to Saudi Arabia to see how America's staunchest Arab ally is defending itself - and how it may be fanning the flames of global militancy. 'Global Jihad' - In the summer of 2014, a group calling themselves the Islamic State, or ISIS, shocked the world by taking over large territories in Iraq and Syria, and committing headline-grabbing atrocities in the process. In the face of international condemnation, would-be fighters from Western countries flocked to join ISIS in their self-styled utopia. Gianna Toboni travels to Europe to meet some of the young men drawn to ISIS's call, and visits with American Navy strike pilots working to roll back the Islamic State's gains.