In a decade-long campaign to change the course of world history through extreme acts of violence, ISIS has been called the most dangerous terrorist group in history. FRONTLINE traces the growth of the Islamic State in The Secret History of ISIS while also investigating the repeated warnings of the threat by senior global policymakers.

Starting with the Bush Administration’s invasions of Afghanistan and Iraq, followed by the growth of the insurgency during the Iraqi occupation, the killing of Osama Bin Laden and the eventual rise of the Islamic State, the story of the war on terror feels familiar fifteen years after the 9/11 attacks. However, what few know is that the American government, under two presidents, allowed and even contributed to the growth of a radical and violent terrorist group that has now achieved more than even Bin Laden could have imagined. The Secret History of ISIS reveals how two terrorist leaders—Abu Musab al-Zarqawi and Abu Bakr al-Baghdadi—created and executed an ingenious plan to build a radical terrorist caliphate while senior American policymakers ignored repeated warnings about what was happening. Drawing on interviews with senior officials, newly uncovered documents, audio recordings and jihadist videos, the film asks why the American government did not recognize the threat in time to effectively counter what would become a deadly challenge to global security.