The US public television's flagship public affairs programme, Frontline, produced a 60-minute documentary on "black money" -- the secret payments that make up the shadowy world of international bribery. It reveals how multinational companies create slush funds and set up front companies to obtain business and contracts. In describing the crackdown on these practices, the documentary focuses on BAE Systems and allegations about its billion dollar bribes. It includes an interview with former Serious Fraud Office (SFO) Director Robert Wardle, who describes as "blackmail" the Saudi threat to withdraw intelligence cooperation with the UK if the SFO's BAE-Saudi investigation continued.