(CNN) - Greg Mortenson, the high-profile advocate of girls' education in Afghanistan and Pakistan, has been forced to defend his best-selling book "Three Cups of Tea: One Man's Mission to Fight Terrorism and Build Nations ... One School at a Time," against charges that key stories in it are false.
Mortenson shot to international fame with the book, which describes his getting lost in an effort to climb K2, the world's second-highest peak, being rescued by Pakistani villagers in the village of Korphe and vowing to return there to build a school for local girls.
He also claims to have been captured by the Taliban and held for several days before being released.
Another best selling-author, however - Jon Krakauer of "Into Thin Air" fame - told a CBS "60 Minutes" investigation that aired Sunday that the story is not true.
"It's a beautiful story, and it's a lie," Krakauer tells the program. CNN's national security analyst, Peter Bergen, shares that belief on CNN's American Morning.