By virtue of their name, stealth fighters -- such as the F-117 or B-2 bomber -- were made to do their work undercover. How do they avoid being detected by radar? They're made up of some of the most technologically advanced materials and are designed to meet the highest standards -- two factors that add up to a price tag of billions. This "Modern Marvels" episode interviews stealth experts and pilots to demystify the plane's enormous capabilities.