Saudi's current ruler is King Salman. Breaking with tradition, he has no plans to hand power over to his brothers and named his son Mohammed Bin Salman (MBS)- as Crown Prince last year. MBS has been quick to stamp his authority on the family and the nation, detaining hundreds of super-wealthy relatives and others at the Ritz Carlton hotel in Riyadh. MBS is cracking down on his miscreant cousins - but is being banged up in the Ritz really so tough? And finally, can he reform Saudi Arabia to a more moderate Islam? Nexus with Matthew Moore