Netflix's show Zero Day, starring Robert De Niro and Jesse Plemons, depicts a frightening possibility. What is a zero day and could it happen in real life?

Let's break down the explosive series finale of Netflix's "Zero Day," a cautionary tale about autocracy, misinformation and cyberterrorism.

As former U.S. president turned special commission investigator George Mullen ( Robert De Niro) delivers a climactic closing speech in the final scene of Netflix's new political thriller Zero Day, it's this admission that gets to the heart of the show's message about the importance of truth in today's world.