In the Century XXV, a virus exterminated most of the population of Earth, and the last city is Bregna, which is ruled by Trevor Goodchild (Marton Csokas) and protected by wall from the outside world. A resistance group entitled Monicans and led by The Handler (Frances McDormand), assigns the assassin Aeon Flux (Charlize Theron) to kill Trevor and overthrow the government. However, Aeon Flux discloses a scheme plotted by Oren Goodchild (Jonny Lee Miller) against his brother Trevor and she resolves to protect Trevor instead of killing him.