Rio de Janeiro celebrates winning the 2016 Olympic bid, and two weeks later a police helicopter is shot down by drug traffickers over the city's slums. Fault Lines follows the government's response: an intensified military crackdown on the favelas. The film goes into Cantagalo, a hillside slum minutes from Rio's beaches recently taken from the Red Command gang, where BOPE, the military police's special forces unit, now runs regular patrols and checkpoints screen everyone entering or leaving. Residents describe living under what feels like occupation, and bullet holes scarring the walls of their homes point to frequent shootouts between police and traffickers. A Human Rights Watch report cited in the film accuses police in Rio and Sao Paulo of killing more than 11,000 people since 2003, alleging that many were executed at point blank range, that many victims were innocent, and that officers sometimes tried to cover up the killings afterward. The episode weighs the security operation against its cost to ordinary residents caught in between.