In the late 1990s, Belgian detective Patrick Peys joined the Diamond Squad. Based in Antwerp's Diamond District, this was the world's first police unit dedicated to solving diamond crime. And soon, Patrick would face the most baffling case of his career when a group of thieves pulled off what seemed to be the perfect robbery. They broke into one of the most heavily-guarded vaults in the Diamond District and stole $100m dollars' worth of jewels. It was the biggest diamond robbery in history. No one saw the thieves coming in, or out. But what followed was a trail of strange clues leading to a mysterious criminal mastermind and a school for felons.

This episode was first broadcast on 10 March, 2019.

Presenter: Emily Webb

Producer: Maryam Maruf

Image: Diamonds

Credit: Olivier Polet/Corbis via Getty Images