 A former USDA voracious insect specialist who is now a college professor, Rierdon (Lawless), in search of a simpler life, has moved to Louisiana with her husband, Dryer (Neal), and their two daughters. But her life becomes more complicated when one of her students is found dead with his body covered in mysterious puncture marks and completely depleted of blood. When two of Rierdon s students are implicated in the boy s death, she immediately gets caught up in the investigation and discovers that the student was killed by a swarm of bats. When other attacks occur and more people are found dead in a similar fashion, evidence leads Rierdon to discover that these are not ordinary bats, but aggressive vampire bats that have mutated due to a tainted water supply. Though she tries to discourage them, several of her students volunteer to help in the investigation, which could all put them in grave danger. But Rierdon knows that she doesn t have a choice and must find a way to halt the bats  deadly progress. Brett Butler stars as Rierdon s strong willed sister-in-law, Shelly; Bottoms portrays the town s mayor, Hank Poelker; and Ferguson has a cameo as a fisherman.