On September 15, 2008, Lehman Brothers filed for bankruptcy, the largest corporate collapse in American history, and this BBC film investigates how a 158-year-old investment bank got there. It traces the firm's slide from a cotton-trading partnership founded in Alabama into a Wall Street giant that gorged on subprime mortgage securities, then follows the frantic weekend of meetings at the New York Federal Reserve where Treasury Secretary Hank Paulson, Fed chief Ben Bernanke, and rival bank chiefs decided whether to save it. Interviews with bankers, regulators, and journalists who lived through the crisis lay out why potential buyers Bank of America and Barclays walked away, and why the government let Lehman fail while rescuing other institutions. The film treats the bankruptcy as a hinge point, the moment credit markets froze worldwide and a housing problem became a global recession. Archive news footage of traders carrying boxes out of Lehman's Canary Wharf and New York offices supplies the images that came to define the crash.