This episode tells the inside story of how some of the most prominent and richest Saudi royals were caught up in the purge. The detentions opened the door on a highly secret world of kickbacks and bribes on a monumental scale, which have also embroiled many foreign governments and some of the world's leading companies.

This episode looks at how the family stays in power. The film features some of those who have worked for Saudi princes. They describe how the wealth allowed lives of privilege and pleasure out of the spotlight, but the growth of social media has meant Saudis are getting increasing insight into the behaviour of their rulers, including their transgressions. With this crucially important country facing a historic crossroads, the programme asks what the future holds for Saudi Arabia and the rest of the world.

Since the Kingdom of Saudi Arabia was constituted in 1932, inexhaustible wealth has granted the Kingdom's ruling royal family total power at home and the freedom to act with relative impunity abroad. A growing regional confrontation with Iran has now…