The film begins with an abandoned house, inhabited by a group of vampire bats, which seem to be mutations of the local population.

Later, in the forests nearby, people begin to find many dead corpses of deer and local animals, with multiple bites on their bodies and their blood completely drained.

While the corpses are studied, one student from the class of Physician/Doctor Maddy Rierdon (Lucy Lawless) gets chased in the forest by something that knocks him down and kills him.

The next morning, police find the drained bodies and, with Maddy's presence at the scene, they are able to recognize some excreta of bats.

A problem is encountered as Maddy is attacked in the underground by one of the policeman, who turns out to be an agent working for the company which has been contaminating the water sources and is therefore responsible for the bats' mutation.

Three months later, Maddy is married and sitting with her children in front of the house where they eliminated the first population of the vampire bats.