QAnon supporters say US President Donald Trump is saving the world from an elite cult of Satan-worshipping paedophiles made up of Democratic Party politicians, billionaires and Hollywood celebrities.
Many of the theories repeat centuries-old anti-Semitic propaganda.
Now, it is also growing in other parts of the world, particularly the United Kingdom and Germany.
Presenter: Mohammed Jamjoom
Sergey Lagodinsky – Member of the European Parliament
Caroline Sinders – Weizenbaum Institute and the Harvard Kennedy School
Ulrich Brueckner – Stanford University, Berlin