Part 1 of this Doc Zone series looks at how greed and recklessness by the titans of Wall Street precipitates the largest financial crash since the Great Depression. It outlines the key triggers in this September 2008 meltdown, including easy lending in the U.S. housing market, the extravagant earnings of business leaders and a complex banking system with few safeguards. It was left to US Treasury Secretary Hank Paulson, himself a former Wall Street banker, to try and avert further disaster.