Louis Theroux is set to explore the world of US rap and hip-hop as part of a new three-part documentary series.The BBC Two series, titled Forbidden America, will explore the impact of the internet and social media on some of the most controversial corners of American entertainment in a trilogy of one-hour films.One episode will see the filmmaker immerse himself in the rap and hip-hop scenes in the southern states, notably Florida, as stakes are raised in the world of constant social media