“When it was my turn, they took me blindfolded,” the thief said. “Suddenly I felt a pain in my right hand that was out of this world. My hand had just been chopped off.” This is Gao, once the seat of an empire, and then a glorified village, and now a city the size of Scranton under the boot of its Islamist conquerors. Gao has become a place where thieves have their hands cut off, where women are forced to wear the stifling Hijab in 113 degree heat or be lashed and where unmarried couples are stoned to death. Borders...