Penny Castro survived the biowarfare apocalypse and created a family. Her post-apocalyptic idyll on their citrus ranch is interrupted by the US government's plan to stop another attack...and get some revenge. Penny and husband Alex, along with others, are drafted to carry out the plan—in their case, forced to do so by the government's kidnapping of their young children. But the enemy has surprises awaiting them when a submarine delivers them to that foreign shore.