After Sarah Douglas is attacked and infected with the blood of a gargoyle-like creature, the cancer that riddled her body vanishes. The attack draws the attention of Doctor Scott, the scientist who inadvertently was responsible for infecting a colony of bats, and changing them into intelligent creatures that could threaten mankind.
As the infected blood slowly transforms Sarah's body, she is caught in the middle of a horrific war between an army of mercenaries and the mutate winged creatures. Watching the creatures gorge themselves on human flesh, she sees her future and fights to maintain her humanity.
With Sarah's blood holding the key to his rearch, the doctor uses his vast resources to try to capture her, along with keeping the outside world at bay. This gets harder to do as the colony expands its territory further away from the 'Devil's Claw' and members of the local population begin to disappear.