By Edward Nawotka

NORTH KOREA: Author Mike Kim spent four years in China helping hundreds of refugees from North Korea cross the border and reach safety. His book Escaping North Korea documents his experiences. It’s a stunning story of courage, both his own and that of the escapees. Though the book appeared last year, Kim continues to be an evangelist for the cause. His recent efforts include a lecture at Oxford University and a visit to The Daily Show (clip below), where he spoke about dodging assassins and the curious way in which North Koreans are taught math: If I a grenade is thrown and kills two Americans and another grenade is thrown and kills three Americans, how many Americans are killed?

READ: More about Mike Kim’s cause on his Web site.

LISTEN: To a podcast of his talk at Oxford University.