An ISIS terrorist planned to kill more than 500 people. He would have succeeded except for three American friends who refused to give in to fear. On August 21, 2015, Ayoub El-Khazzani boarded train #9364 in Brussels, bound for Paris. There could be no doubt about his mission: he had an AK-47, a pistol, a box cutter, and enough ammunition to obliterate every passenger on board. Slipping into the bathroom in secret, he armed his weapons...