Not all is as it seems with Dr Ruja's revolutionary cryptocurrency, OneCoin.
The Missing Cryptoqueen is an eight-part series for BBC Sounds, with new episodes every Thursday.
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