Two high school sisters, Samantha (Kelli Maroney) and Regina (Catherine Mary Stewart) awake one morning to find that the entirety of humanity has been decimated when the Earth passes through the tail of Haley’s comet. Anyone who was not surrounded by steel when the event happened has perished. The girls begin to journey outside and encounter various survivors and eventually stumble upon a group of scientists who predicted the comet’s effect and were able to build a steel fortress to protect them. The scientists alert the girls to the effect that the comet will have on the living, by turning them into flesh eating zombies. The girls then flee the scientists who need their blood to create a vaccine and brave the new world and the mutated zombie-like humans that inhabit it.