Sakandar Hayat wanted it to be a special Ramadan. He and his teenage boy Arafat left northwestern China and crossed the border into Hayat’s native Pakistan. It was a journey to bring father and son closer together. But it would end up tearing their family apart. The two had been in Pakistan for three weeks when they received a phone call from back home in the Chinese region of Xinjiang. Hayat’s wife, an ethnic Uighur, had been...