Joshua Oppenheimer's films include the BAFTA award-winning and Oscar-nominated The Act of Killing (2012), and the companion piece The Look of Silence (2014) - winner of the Grand Jury prize at the 2014 Venice Film Festival. He is the artistic director of the Centre for Documentary and Experimental Film at the University of Westminster and has worked for over a decade with militias, death squads and their victims to explore the relationship between political violence and the public imagination. In this in-depth masterclass, BBC1 Film Programme critic Danny Leigh, unpicks Joshua's methods and motivations and explore the meaning of his controversial and boundary-pushing films.