Panorama: The superdollar plot was broadcast on BBC One on Sunday, 20 June 2004 at 22:15 BST
In 1998, a small-time Birmingham criminal walked into a Bureau de Change in Stafford to change a batch of US $100 bills.
His 30 second transaction resulted in a huge undercover police operation, as a team of detectives crossed the globe on the trail of a shadowy and sophisticated counterfeiting cartel.
The notes that turned up in Birmingham were "superdollars" - the most sophisticated counterfeit bill ever produced and undetectable even to currency experts.
Believed to be printed on an industrial scale in the isolated state of North Korea, superdollars have become the currency of choice for the criminal elite who are granted access to them.
With unique access to undercover police surveillance material, Panorama revisits the case and goes beyond the police investigation.
We trace the route of the superdollar distribution network from the presses of North Korea to Moscow's mafia-run underworld, and from former spies to a prominent Irish Republican who supplies them to British criminals in huge quantities.
This man, accused of being a kingpin in the superdollar network, has never been charged or even arrested for counterfeiting.
Producer: Andrew Martin
Reporter: Declan Lawn
Deputy Editor: Andrew Bell
Editor: Mike Robinson