When a U.S. military helicopter was shot down in Afghanistan, Georgia native Gerry Neel and his elite unit were sent in to rescue survivors. Gunfire rained down, killing three of Neel's buddies. Back at the barracks, Neel mourned the deaths of his fellow Airborne Rangers while clutching a laminated photo of his wife and son —- his comfort amid the chaos of war. An hour after he finally fell asleep, he was awakened with dreadful news: His 20-month-old son, Hunter, had fallen to his death from the ninth-floor balcony of a downtown Atlanta hotel. It took Neel three days to...