Diplomatic Security special agent David Ubben waits silently, his M-4 assault rifle at the ready as he hides deep in the dark inside the villa that serves as the United States Consulate in Benghazi, Libya. Ubben’s assignment is close protection for U.S. Ambassador J. Christopher Stevens, which isn’t always easy. Stevens, a former Peace Corps volunteer, likes to get out among the people in the countries where he serves, especially Libya, which he helped to liberate from Muammar Gaddafi during the war last year. But even he has started to believe that al Qaeda is gunning for him, and on this day, the 11th anniversary of the Sept. 11 attacks on the United States, Stevens has let himself be persuaded to hold all his meetings behind the nine-foot walls and the coils of concertina wire that surround the Benghazi consulate.