Imagine a deadly pathogen that, once created, could infect any person in any part of the globe within seconds. No need to wait for travellers, trains, or air traffic to spread it, all you need is an internet connection. In this investigation, Pulitzer Prize winner James Ball decodes the cryptic language of the online right and with a surgeon’s precision tracks the spread of QAnon, the world’s first digital pandemic. QAnon began as an internet community dedicated to supporting President Trump and intent on outing a global cabal of human traffickers. A short, cryptic message posted by an anonymous user to a niche internet forum in 2017 was the spark that ignited a global movement. What started as a macabre game of virtual make-believe quickly spiralled into the spread of virulently hateful, dangerous messaging – which turned into tragic, violent actions.