Sunday at 9p ET in a Fox Files exclusive, we bring you inside the hermit kingdom of North Korea to see how an underground railroad is helping people escape from the most repressive place on earth. Bill Hemmer talks to two Korean Americans who are leading defectors to freedom. For the first time, a defector shares the harrowing story of how he fled with his family to China, Laos and eventually into South Korea.

Watch a sneak peek below and tune in to Fox Files, Sunday at 9p ET.