"I was instrumental. I was at the heart of it." Chris Wylie, former Cambridge Analytica director of research Four Corners brings you the undercover investigation that has left social media giant Facebook reeling through the unmasking of the secretive political consulting firm Cambridge Analytica. Four months in the making, this ITN investigation for Channel 4 in Britain used hidden cameras to reveal the tactics used by the UK firm Cambridge Anayltica to influence elections and undermine the democratic process in several countries.