<p>Dr Ruja promised financial revolution. And then, two years ago, she disappeared. Why?</p><p>The Missing Cryptoqueen is an eight-part series for BBC Sounds, with new episodes every Thursday.</p><p>Presenter: Jamie Bartlett Producer: Georgia Catt Story consultant: Chris Berube Editor: Philip Sellars Original music and sound design: Phil Channell Original music and vocals: Dessislava Stefanova and the London Bulgarian Choir</p>