When a group of Ninth graders go on a field trip to a local cave that has been closed for 50 years because of rumors the army once stored dangerous chemicals there, it becomes a game of survival after they are attacked by mutated bats. The reluctant hero is a kid named Sean who must step up and take charge if he is going to protect himself and his close-knit group of friends. Things become even more complicated when the kids learn their remote little town has also been invaded by the zombie bats.
