When a catastrophe occurs, the questions immediately arise. How did it happen? Who was responsible? And can it happen again? Often, the tragedy isn't triggered by a single cause but by a string of errors. This series investigates four of modern history's worst disasters-the JFK assassination, the 9/11 attack, the 737 Max crashes, and the Deepwater Horizon explosion-and reveals ten crucial mistakes behind each one. Weaving archive and interviews, we detail what went wrong and what steps have been taken to prevent similar events from reoccurring.