In 2018, Italy's Morandi Bridge collapsed, tragically killing 43 people. For 50 years, the iconic bridge had withstood the elements—and stress from ever-increasing traffic. What went wrong that fateful day? And how can new engineering technology protect bridge infrastructure to prevent such tragic failures in the future? Through eyewitness testimony, expert interviews, and dramatic archival footage, NOVA investigates the Morandi disaster and other deadly bridge collapses across the United States.