FRONTLINE investigates the causes of the worst economic crisis in 70 years and how the government responded.  The film chronicles the inside stories of the Bear Stearns deal, Lehman Brothers collapse, the propping up of insurance giant AIG and the $700 billion bailout.  It also examines what Treasury Secretary Henry Paulson and Federal Reserve Chairman Ben Bernanke didn't see, couldn't stop and haven't been able to fix.