One Sunday morning before church, when Welles Crowther was a young boy, his father gave him a red handkerchief for his back pocket. Welles kept it with him that day, and just about every day to come; it became a fixture and his signature. Welles became a volunteer with the local fire department in New York. When the Twin Towers fell, Welles's parents had no idea what happened to him. In the unbearable days that followed, they came to accept that he would never come home. But the mystery of his final hours persisted. Eight months after the attacks, however, Welles's mother read a news account from several survivors, badly hurt on the 78th floor of the South Tower, who said they and others had been led to safety by a stranger, carrying a woman on his back, down nearly twenty flights of stairs. After leading them down, the young man turned around. "I'm going back up," was all he said. The survivors didn't know his name, but despite the smoke and panic, one of them remembered a single detail clearly: the man was wearing a red bandanna.--