Carolyn Yeager continues her investigation into "what makes a traitor" by looking at The Cambridge Five: Upper-class British Trinity College students who began their unlikely career as Communist sympathizers and members of secret 'discussion group' clubs. Anthony Blunt, Guy Burgess, Kim Philby and Donald Maclean went on to become full-fledged Soviet agents during WWII and the Cold War. Guy, Kim and Donald eventually defected to the Soviet Union and died there. Blunt and Cairncross were outed but never prosecuted, remaining in Britain. But why did they want to do it in the first place? That is never satisfactorily explained by them but Carolyn offers some suggestions.