At 24, [Christopher Wylie] came up with an idea that led to the foundation of a company called Cambridge Analytica, a data analytics firm that went on to claim a major role in the Leave campaign for Britain's EU membership referendum, and later became a key figure in digital operations during Donald Trump's election campaign. In 2014, Steve Bannon ... was Wylie's boss. And Robert Mercer, the secretive US hedge-fund billionaire and Republican donor, was Cambridge Analytica's investor. The idea they bought into was to bring big data and social media to an established military methodology - information operations" - then turn it on the US electorate. By [2017], Steve Bannon had become Trump's chief strategist. Cambridge Analytica's parent company, SCL, had won contracts with the US State Department and was pitching to the Pentagon, and Wylie was genuinely freaked out. "It's insane," he told me one night. "The company has created psychological profiles of 230 million Americans. And now they want to work with the Pentagon? It's like Nixon on steroids." He ended up showing me a tranche of documents that laid out the secret workings behind Cambridge Analytica. Wylie ... came up with a plan to harvest the Facebook profiles of millions of people in the US, and to use their private and personal information to create sophisticated psychological and political profiles. And then target them with political ads designed to work on their particular psychological makeup.