One year after the murder of columnist Jamal Khashoggi, a two-hour FRONTLINE documentary investigates the rise and rule of Crown Prince Mohammed bin Salman of Saudi Arabia (MBS). Correspondent Martin Smith, who has covered the Middle East for FRONTLINE for 20 years, examines the crown prince's vision for the future, his handling of dissent, his relationship with the United States — and his ties to Khashoggi's killing.