Netflix's new Robert De Niro-led political drama ends with a shocking revelation about the Zero Day attackThe season finale of Netflix’s new political thriller Zero Day finally reveals who is behind the nationwide cyberattack that took the lives of more than 3,

Proteus is a secret government weapon designed to cause brain damage remotely without leaving any physical evidence.

By the end of the finale, Mullen seems to have kept the symptoms mostly at bay as he returns to his quiet private life. The final sequence reveals President Mullen burning the pages of his memoir manuscript—his legacy has been irrevocably altered for better or worse—before heading out for a walk with his dog.