As a last hurrah after college, pals Jeff, Karen, Paul, Marcy and Bert start a holiday deep into the mountains. With the top down and the music up, they drive to a remote cabin to enjoy their last days of decadence before getting in the working world. Someone gets ill. Karen's skin starts to bubble and burn as something grows inside her, tunneling underneath her flesh. As the others dispute about how to save her, they look at one another and recognize that any one of them might likewise have it. What began as a struggle against the disease soon develops into a battle versus pals, as the worry of contagion drives them to switch on each other.