The Fifth Power (1962)

Foreign agents from an unidentified nation clandestinely install radio and TV antennas in Rio de Janeiro devices that emit subliminal waves that alter the perception of the population. They aim to transform the people into an aggressive and imbecile mass, leading the country to chaos, allowing the government to be taken to usurp Brazil's natural wealth. A journalist, Carlos, accompanied by chemist Laura Leal, begins to investigate a series of facts and discovers those responsible for the disturbances.