This interview contains spoilers from all six episodes of "Zero Day," now streaming on Netflix. Lizzy Caplan always knew that her character, Congresswoman and former First Daughter Alexandra Mullen, was behind the catastrophic cyberattack that incited the existential and moral panic that runs through "Zero Day.

For Lizzy Caplan, joining Netflix's "Zero Day" was an easy decision to make, citing Robert De Niro's involvement, as well as the "solid" credentials of co-creators Eric Newman, Noah Oppenheim and Michael Schmidt.

Actor Lizzy Caplan stops by TODAY to share details about starring alongside legendary actor Robert De Niro in the new Netflix thriller “Zero Day.” Caplan also opens up about moving with her family from Los Angeles to New York City and discusses the lasting relatability “Mean Girls” has to high schoolers.

I loved those scenes,” Lizzy Caplan told DECIDER. “We knew from very early on that there was a rich history that we wanted to convey.” That history includes Alex’s deceased brother, Nick (Jackson Eick).

The iconic film actor plays a former U.S. president put in an impossible position in the Netflix political thriller.