Former U.S. Treasury Secretary Hank Paulson describes the moment he knew Lehman Brothers' fall meant the global financial system was at risk.
Watch the video above for an in-depth conversation between CNBC's Andrew Ross Sorkin and Paulson about a historic week on Wall Street.
The CNBC Original "Crisis On Wall Street: The Week That Shook The World" premieres Wednesday, 10 p.m. ET/PT.
