Madonna of the Yarnwinder
(The Buccleuch Madonna)

The Missing Madonna, which is available from 25 August on BBC Sounds, marks the 20th anniversary of an audacious art heist that set the record for the most valuable painting ever to be stolen in Britain.

The nine-part series features never-before-heard secret recordings and asks serious questions about the way in which stolen artwork is returned in the UK.

The compelling tale, brimming with twists, turns and double-crosses, begins with two men posing as tourists, overpowering a Drumlanrig Castle guide, snatching the multi-million-pound masterpiece and fleeing the scene in a battered white Volkswagen Golf.

Despite a high-profile investigation involving the FBI, plus the promise of a substantial reward, the painting disappeared into the criminal underworld. Its owner, the Duke of Buccleuch, could only wait and hope.

Four years later, the masterpiece appeared to resurface on Merseyside when a mysterious man walked into a Liverpool pub and asked to speak to the two men behind the website StolenStuffReunited.com.

Those two men were Robbie Graham and Jack Doyle – friends and business partners who ran their own PI firm, Crown Private Investigations, in addition to their website. Sensing an opportunity to do something truly historic and collect a big reward, Robbie and Jackie assembled a crack team to help them get the painting back.

For a while it seemed as if everything was progressing well, but after a series of dramatic twists, including a nervy meeting in a village pub car park, the two private investigators were faced with an outcome they never could have predicted.

All episodes of The Missing Madonna will be available on BBC Sounds from 25 August