Sean honors the heroes whose courage on September 11th continues to shape America 25 years later. Frank Siller shares the story of his brother Stephen, who strapped on his firefighter gear and ran through the Brooklyn-Battery Tunnel toward the World Trade Center, ultimately giving his life to help others. Sean also looks at the continuing mission of Tunnel to Towers and speaks with former Secret Service agent Patrick Sullivan about the airport-security vulnerabilities uncovered before 9/11 and the lessons that still matter today.