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.

"I love a political thriller. I really love being in New York," she added. "So it was as close to a no brainer as you can get." Caplan portrays George Mullen's (De Niro) daughter, Alexandra, who is a young New York congresswoman working hard to distance herself from her father's political legacy and establish herself in her own right.