In this series we've learned that there are more than three million spies around the world eyeing the U.S. We've examined who they are and the tactics they use. A former U.S. agent gave us a glimpse into a day in the life of American spies. Now, in the conclusion, what should we expect in the future? What tactics are coming? Where will the spies originate from? And can the U.S. handle the threat?