This first episode features the US Army Ranger School, which is considered to have the toughest combat course on the planet.

For sixty-one days and nights, this extreme training replicates the nonstop stress of warfare. Soldiers sleep an average of three hours a night and receive just one meal per day. They train continuously, running missions 20 hours straight in mountains, swamps and dense woodlands. Most lose 20 or more pounds before it’s over, and many quit or fail the course along the way.

Only one in three make it though.