To be trapped behind enemy lines is every soldier's worst nightmare: a situation all fighters train for, few experience and even fewer survive. From the producers of National Geographic Channel's critically acclaimed Locked Up Abroad and Inside the Hunt for the Boston Bombers, new series "No Man Left Behind" combines gripping personal testimony with vivid reenactments and archival footage to shed light on the stories of modern war heroes and special agents who overcame incredible odds in some of the most hostile environments on earth.