On January 30, 1918, a young man “with the appearance of a well-educated, debonair foreigner” arrived at the U.S. customs station in Nogales, Arizona, located on the border with Mexico. After politely informing the customs inspector that he had come to complete his draft registration questionnaire and meet a friend in San Francisco, he was approved to cross the border into the United States. Lothar Witzke, the most dangerous German agent in the western hemisphere had reached his destination. His assignment: launch a campaign of sabotage, insurrection, and murder to destabilize the American home front. The terror campaign would be devastating - unless it could be stopped by U.S. counterintelligence. The Witzke mission was the intelligence game played at its highest level - a plan for destruction on a massive scale, violent insurrection, and assassination, complete with master spies and double agents, diabolical sabotage devices, secret codes, and invisible ink. To look at these forgotten elements of German sabotage and assassination plots in the United States during World War One is today’s guest, Bill Mills, author of “ Agents of the Iron Cross.”