When a population of bats in a small Texas town starts attacking the unsuspecting citizens, Dr. Sheila Casper (Dina Meyer), a zoologist specializing in the species, is called in to investigate. With the help of her assistant and the local sheriff (Lou Diamond Phillips), strange details about the bats begin to emerge: It’s discovered that they are the product of a governmental experiment gone awry. With people dying and the military threatening to take action, a solution must be found.