For Lucy, fear of nuclear war had been with her since she was a child (from the Guardian):
"I remember my dad saying you'd need to build a shelter, and you'd need a gun to keep the neighbours out," says Walker, "and my mother saying she'd take a suicide pill anyway. To hear these ideas coming out of the mouths of your otherwise sensible parents, it didn't compute. It was so shocking and outrageous."Here is the official trailer for Countdown to Zero:
Interestingly, Valerie Plame served as a consultant for the movie (starting around 1:50)
Click here to go to the official website.