A white cross rising above the Macacos slum marks the spot where people are burned alive. A starving horse, his ribs poking out, is hitched close by with a thin rope. A nearby soccer field is dotted with pieces of melted rubber. No games are played here. The Amigos dos Amigos gang that runs this favela has a ritual: Members stack tires around their enemies, pour in gasoline and light the tires on fire. This is called microwaving. Black smoke rises into the air. At a school down the hill, near the famous soccer stadium where the 2016 Olympic opening ceremonies will be held, the students hear the screams and cover their ears.