QAnon is the online movement spawned by Q, a poster on the anonymous message board 4chan. In October 2017, they began leaving a series of gnomic posts riven with strange imagery – “drops.” Claiming to be a US official with a high-level security clearance, Q informed fellow users that the United States was secretly controlled by a clique of pedophiles and traitors encompassing much of the Democratic party and the intelligence services. But Donald Trump, who had recently been elected president, was alive to the danger. With the aid of friendly “deep state” elements, Trump was working behind the scenes...