In 2016, on stage at Wembley Arena in front of thousands of 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 promised that the cryptocurrency she had created – OneCoin – would not only earn its investors untold fortunes but also change the world.

A year later investors had bought more than $4 billion-worth of OneCoin. The true believers lived all over the world – in the USA, Pakistan, Hong Kong, Yemen, the UK, Brazil and beyond. But in October 2017 Ruja Ignatova disappeared from public view, and it slowly became clear to her followers that her revolutionary cryptocurrency was in fact one of the biggest scams in history.

In June 2022 Jamie Bartlett came to Intelligence Squared with Layla Begum and Carl Miller to tell the shocking story of Dr Ruja and OneCoin. He drew from his new book The Missing Cryptoqueen to explain how organised crime, influencer culture and hype around cryptocurrencies combined to dupe some of the world’s poorest people into thinking they had discovered a route out of poverty. Bartlett also discussed the broader questions around cryptocurrency’s future and his ongoing hunt to find the cryptoqueen, who has been in hiding for five years and was recently added to EUROPOL’s most wanted list.