In 2008, American journalist Jere Van Dyk was kidnapped and held for 45 days. At the time, he had no idea who his kidnappers were. They demanded a ransom and the release of three of their comrades from Guantanamo, yet they hinted at their ties to Pakistan and to the Haqqani network, a uniquely powerful group that now holds the balance of power in large parts of Afghanistan and the tribal areas of Pakistan. After his release, Van Dyk wrote a book about...