In 2010, two Harvard economists published a blockbuster paper claiming that countries with debt above 90% of GDP see their economies collapse — a finding that quietly became the justification for a decade of brutal austerity policies across Europe and beyond. The only problem? A grad student named Thomas Herndon tried to replicate the results for a homework assignment and discovered a Excel formula that skipped five countries entirely. We dig into how a hidden spreadsheet error shaped the lives of millions of people who never once opened Microsoft Office.