Mohammed bin Salman, the young crown prince and de facto ruler of Saudi Arabia, has established two things beyond doubt since his father, King Salman, ascended the throne in 2015 and handed him the keys to the kingdom. He aims to end the House of Saud’s consensual model of an absolute monarchy with no absolute monarch and, instead, take all the reins of power. And he intends to power forward with social and economic reform in a kingdom established under theocratic tutelage, where change has traditionally been driven at speeds between slow and stop.

This is a breathtaking gamble by a headstrong and untried young prince, aged 32, who is seeking a new source of legitimacy by embodying the pent-up aspirations of a young people, two-thirds of whom are under 30.

At the beginning of November, only days after a so-called Davos in the Desert conference had brought global investors flocking to Riyadh, Prince Mohammed (or MbS, as he’s colloquially known) rolled the dice again by rounding up leading lights in the kingdom’s political and business elite. He ordered the detention of 11 princes, more than three dozen current and former ministers, and billionaires galore, packing them into the venue for the business summit—the capital’s regal Ritz Carlton hotel.

Among those caught in the crown prince’s gilded cage are Prince Alwaleed bin Talal, the flamboyant multi-billionaire tycoon, and Prince Miteb bin Abdullah, minister and former chief of Saudi Arabia’s powerful National Guard. Also arrested was Sheikh Waleed al-Ibrahim, brother-in-law of the late King Fahd and billionaire media baron.

Billed as a crackdown on corruption, the MbS purge is political in two main senses.

First, ever since MbS deposed then crown prince Mohammed bin Nayef—his cousin and veteran interior minister—in a June palace coup, it was only a matter of time before he went after a just as powerful cousin: Miteb bin Abdullah, son of the late King Abdullah. Prince Miteb, 65, was a plausible rival for the throne, and his 100,000-strong and well-equipped National Guard, rooted in the kingdom’s intricate tribal networks, was the last remaining autonomous fief—another army MbS had to neutralise after seizing control of interior ministry forces this summer. Taking out Miteb has rekindled fevered speculation that King Salman, 82, will soon abdicate in favour of MbS, his favourite son.

Second, an anti-corruption swoop is profoundly populist, especially if MbS succeeds in separating the fabulously wealthy targets from big chunks of their assets.

Targeting an investor of global reach and renown such as Prince Alwaleed risks questions about the investment climate in Saudi Arabia, as Prince Mohammed pursues his much-trumpeted Vision 2030. This reform program aims to wean the kingdom off fast-diminishing hydrocarbon revenue, boost private investment and create what he hopes will become the world’s biggest sovereign wealth fund, built around the planned part-privatisation of Saudi Aramco, the state oil company.

A raid on the rich to top up a treasury crippled by falling oil prices may play well as Saudis accustomed to getting everything from jobs to houses from the state are being asked to accept austerity in place of cradle-to-grave welfare.

To populism at home MbS has added nationalism abroad—above all in the contest for regional hegemony between Sunni Saudi Arabia and Shia Iran. As defence minister as well as economic tsar, Prince Mohammed has been pushing back against the Islamic Republic and its successful forging of a network of Iranian proxies from Baghdad to Beirut. But his hawkish foreign policy isn’t going well.

Saudi Arabia is still bogged down in Yemen after more than two years, against rag-tag Houthi rebels Riyadh could not deal with even before Iran and its allies gave them some support. His attempt to cripple the maverick and gas-rich emirate of Qatar with a blockade has had limited success and unsettled the Gulf’s investment climate.

Iran has won in Syria’s civil war and made new strides in Iraq as the Shia militias trained by its revolutionary guards help see off ISIS. MbS has now targeted Hezbollah, the Lebanese paramilitary force that serves as Tehran’s spearhead in this regional trial of strength. On the same day as the round-up in Riyadh, Saad Hariri, the Saudi-backed Lebanese prime minister, read out his resignation on Saudi TV—evidently under duress, now that MbS has decided to bring down a coalition in Beirut that includes and legitimises Hezbollah.

That move sent shockwaves through the region and was seen as reckless by European states anxious about a new conflict triggering more stampedes of refugees. But the crown prince may feel with some reason that he has the wind behind him, given President Donald Trump’s growing belligerence towards Iran, and Israel’s repeated threats that it will go to war to stop Iran and Hezbollah from establishing a permanent base in Syria and to destroy the Lebanese militia’s formidable and growing arsenal of rockets.

Yet the model the crown prince seems to be emulating is that of the United Arab Emirates of Mohammed bin Zayed, its crown prince, de facto ruler and MbS mentor.

That formula is to be: socially liberal, economically open, and firmly shut politically.

MbS has breathed fresh air into the stifling Saudi kingdom. He has defanged the notorious religious police, is chipping away at gender segregation and promoting mixed entertainment, and—in a move that must stick in the craw of the Wahhabi clerical establishment—will next year allow women to drive for the first time.

His next challenge—and arguably the biggest so far—will be to confront the entrenched power of these reactionary clerics, and above all seize back control from them of education. Saudi schools are stuck in a stew of rote learning and sectarian bigotry that cannot conceivably prepare young minds for either private enterprise or a stable society. MbS wants to build a more dynamic economy fired by private investment rather than dwindling oil revenue, yet his methods may be too arbitrary for investors to navigate. As he tries to jump-start the kingdom from the petro-paternalism of an absolute monarchy into a modern state, he seems to discern no link between pluralism and prosperity. His ambition is not in doubt. His judgement will be severely tested.