Glenda Lawson believes her husband was the only U.S. serviceman shot and killed on American soil during World War II. But in 1945, investigators ruled that Billy Lawson died in a "mugging turned ugly." In 2012, Sean O'Brien, learning the ropes of commercial fishing, gets his anchor caught on something underwater. He discovers a German U-boat partially buried in sand, and inside is a frightening cargo. The media pick up the story, and a 35-year-old...