When Russia invaded Ukraine it overturned decades of stability. We trace Vladimir Putin's rise to power from his days as a KGB counterintelligence officer to his emergence as a global power player in the post Cold War era.

Cryptocurrency is the hottest financial product in the world.  

The hype is everywhere, with forms of the digital currency endorsed and advertised by celebrities daring you to invest in this brave new world.  

Not everyone is convinced by the glossy ads and bold claims.

Four Corners investigates what lies behind the slick marketing and big promises to examine if it's a fad, a fraud or the future.