With Carolyn Yeager. What makes a traitor? Why are they hard to spot? Half German-half Russian Sorge has been called the best spy ever. He was probably responsible for the failure of German forces to take Moscow early in the Barbarossa campaign, when it would have made them unstoppable. What motivated him to excel at his chosen career? Are their warning signswe can recognize that would indicate men and women who might be less loyal to their homeland - more ready to help the other side? Sorge's story is a fascinating and instructive one.