There's neither blood nor tanks on the streets of Riyadh, but what has happened in Saudi Arabia in recent days represents a revolution of sorts. King Salman and his son, Crown Prince Mohammed have launched a purge of princes, ministers and potential rivals - part of a grand plan to entrench their power and transform the country. HARDtalk’s Stephen Sackur speaks to Saudi journalist, commentator and current political exile Jamal Khashoggi. Is the Saudi drama about raw power or real reform?