In this unprecedented testimony, whistleblower Christopher Wylie explains how the use of tens of millions of people's personal data and large-scale manipulation operations enabled Donald Trump to gain power, and Brexit be voted in the British referendum. Wylie was the first to denounce the practices of the company he worked for, Cambridge Analytica, and to point fingers at Facebook, WikiLeaks, Russian intelligence services and hackers from around the world who participated, more or less actively, in these operations whose political and geopolitical consequences concern us all.