In 2016, on stage at Wembley Arena in front of thousands of adoring fans, Dr. Ruja Ignatova promised her followers a financial revolution. The future, she said, belonged to cryptocurrencies such as Bitcoin. And the Oxford-educated, self-styled cryptoqueen vowed that she had invented the Bitcoin Killer. OneCoin would not only earn its investors untold fortunes; it would change the world. By March 2017, more than $4 billion had been invested in OneCoin in countries all around the world. But by October 2017, Ruja Ignatova had disappeared, and it slowly became clear that her revolutionary cryptocurrency was not all it seemed. Fortune was left asking, "Is OneCoin the biggest financial fraud in history?" In The Missing Cryptoqueen, acclaimed tech journalist Jamie Bartlett tells the story he began in his smash hit BBC podcast, entering the murky worlds of little-regulated cryptocurrencies and multilevel marketing schemes. Through a globe-crossing investigation into the criminal underworlds, corrupt governments, and the super-rich, he reveals a very modern tale of intrigue, techno-hype and herd madness that allowed OneCoin to become a million-person pyramid scheme--where, at the top, investors were making millions and, at the bottom, people were putting their livelihoods at risk. It's the inside story of the smartest and biggest scam of the 21st Century--and the genius behind it, who is still on the run.