In August 2012, Syrian president Bashar al-Assad was clinging to power in a vicious civil war. When secret intelligence revealed that the dictator might resort to using chemical weapons, President Obama warned that doing so would cross "a red line." Assad did it anyway, bombing the Damascus suburb of Ghouta with sarin gas, killing hundreds of civilians, and forcing Obama to decide if he would mire America in another unpopular war in the Middle East. When Russia offered to broker the removal of Syria's chemical weapons, Obama leapt at the out.

So began an electrifying race to find, remove, and destroy 1,300 tons of chemical weapons in the midst of a raging civil war. The extraordinary little-known effort is a triumph for the Americans, but soon Russia's long game becomes clear: it will do anything to preserve Assad's rule. As America's ability to control events in Syria shrinks, the White House learns that ISIS, building its caliphate in Syria's war-tossed territory, is seeking chemical weapons for itself, with an eye to attack the West. Drawing on astonishing original reporting, Warrick crafts a character-driven narrative that reveals how the United States embarked on a bold adventure to prevent one catastrophe but could not avoid a tragic chain of events that led to another.