Underground railroad worker Phillip Buck, recently released from a Chinese prison, has told Melanie Kirkpatrick about his activities, his arrest, and even his new identity: Pastor Buck is nothing if not determined. In 2002, while in a Southeast Asian country with a group of refugees he had guided there, his apartment in Yanji city, in northeast China, was raided. Nineteen refugees were captured and a copy of his passport was confiscated. With his identity now compromised, Mr. Buck returned to...