The world watches as a comet looms over the earth for days. The masses were told there is nothing to worry about. It was a lie! An eclectic group of survivors huddle together and battle for their only chance to survive against the uprising of the undead while trying to save the fate of mankind. In a twist on the standard zombie movie of the "Night of the Living Dead" series, the zombies here are infected with alien organisms from the thawing comet, not by being bitten. Holed up in an abandoned military blockhouse, the survivors are a mixed bag; a young unmarried couple, a former porn star and her sheltered teenage daughter, a born again fundamentalist preacher, a gay man, an alpha male movie producer/rancher, a couple of soldiers, one male and one female, a high-roller, and the preacher's infected brother, chained up in the basement. Internal strife hampers the group's events to come up with a plan to defeat the zombies pressing in on the chain-link fence surrounding the site; one by one they begin to fall victim, both to the zombies and to each other. The plot takes an even more horrifying turn when vivisecting a couple of male zombies reveals the eventual end of the infection; after their genitals drop off, they become host to rapidly developing alien embryos, with the capability of regenerating whole new bodies if chopped up. Further revelations in the same vein occur when two of the female survivors begin to display symptoms of advanced pregnancy, despite claiming to still be virgins; it becomes clear that is how the infection develops in human females. The teenage daughter of the porn star, under the influence of the alien embryo, seduces the preacher so that the alien fetus can kill him; she dies herself. The rancher abandons the group to hole up in his well equipped and secure ranch. The male half of the young couple finally realizes that his girlfriend is telling the truth when she claims to still be a virgin despite her impending delivery, and the two remain at the blockhouse while the rest of the remaining survivors decide to make a break for it to forage for supplies, only to stall their vehicle outside the gate and be torn to pieces by the zombies. The rancher returns unexpectedly with a load of supplies, realizing he needs companions to join him in his refuge. Under the influence of her alien fetus, the girlfriend shoots and kills the rancher. The young boyfriend attempts to operate on his girlfriend to deliver the alien, and anesthetizes her with some of the ample whiskey supply the rancher brought back; the alien abruptly leaves the girl's body, causing the boy to realize that all the uninfected survivors had described one common factor; all had been drunk at the time of the comet's appearance. Theorizing that the aliens were hypersensitive to alcohol, he doses the dead preacher's zombie brother, still chained in the basement, with whiskey with mixed results; the alien parasite cannot stand the alcohol, but this causes the zombie's head to explode. The boy and the girl, now cured of the alien parasite, leave the compound to try and survive in the outside world, now that they have a weapon against the aliens.