Ciudad Juarez, just across the border from El Paso, gets all the press. But Mexico City is a violent, unpredictable place of big money, greater poverty, drugs, guns, and greed. All but the money are on display in the city’s Iztapalapa slum. I rushed in there one evening past midnight. A man had just been gunned down fleeing his car. The body lay in a pool of blood in a taco stand. All along the rooftops and in the surrounding storefronts, bystanders looked on, whispers of the killers among them.