The group of friends consists of Paul, Karen, Jeff, Marcy, and Bert, who are hoping for a wild weekend filled with drinking and debauchery. However, they soon discover that they are not alone in the woods when they encounter a strange and frightening hermit who warns them to leave.
After an unsettling encounter with the hermit, the group begins to notice strange things happening to their bodies. Karen develops a rash on her skin, and Jeff becomes feverish and delirious. As the days go on, the group's condition worsens, and they soon realize that they have been infected with a deadly virus.
Desperate to find help, the group splits up to seek medical attention. However, they soon discover that the virus has spread beyond their small group and is now affecting the entire town. Panic sets in as the friends realize that they are fighting for their lives against an unstoppable force.
The movie is filled with gruesome scenes of gore and violence, as the virus takes over the bodies of those infected. The group must band together to try and find a way to survive, but as tensions rise, they begin to turn on one another. In the end, only a few of the friends manage to escape with their lives, but the virus continues to spread, leaving the fate of the town unknown.