Dissecting 45 million tweets from the period that followed the Brexit referendum, this book presents an extensive analysis of social media manipulation. The book examines emerging changes in partisan politics, nationalist and populist values, as well as broader societal changes that are feeding into polarization and echo-chamber communication. It pulls the curtain back on the techniques employed to interfere with, and potentially distort, the public discussion. Making complex data accessible to non-technical audiences, this unique post-mortem of the Brexit referendum contributes to our understanding of social media disinformation in the UK and beyond.