Seam heads over to the local reservoir, and notices a body floating in the lake. The marks Sean made on her back are shown to be developing into gruesome wounds like Claire's. Now completely alone, Hannah has a bath and weeps. Hannah urges him to stay, but Sean seems uncomfortable around her after sleeping with her and insists that he "has to get out of" the cabin. Later, Sean tells Hannah that he's going to bring back Daryl so that they can all walk back to civilization. While washing her face, Hannah discovers, with worry, some red marks on her back where Sean grabbed her in the heat of their playful encounter. He goes into the bathroom and attempts to disinfect his penis by pouring Listerine over it. After they finish having playtime, Sean worries about whether Hannah has the disease or not. Hannah brushes him off without heed by saying "Don't worry, I'm healthy!" and continues climbing all over him. Sean expresses concern that they aren't using a condom. He tries to reassure her, but she reiterates that they are all doomed to get sick, to the point where "all you want to do is grab the person next to you and (have playtime with them), because you know you're gonna be dead soon, anyway." She seduces Sean and they begin having wild playtime. Now alone in the cabin, Sean finds Hannah sitting despondently on her bed. Bender speeds off and the father grabs two of his friends (Nathan Gamble and Matthew Broderick) who arm themselves with rifles to go after Bert. His father (Tyler Mane) comes outside and, rather than helping Bender, tries to kill him. The young boy on the bench then runs over and bites Bender, thereby infecting himself. Bender drives to the convenience store that the group visited earlier pleading for a doctor. Hannah yells at him as he flees, upset that he has abandoned her. When Sean and Hannah insist on helping Claire, Daryl runs off into the forest with the remaining beer (the only reliable drinking source).
Bender also realizes that he himself is infected with the virus. The next day, they discover Claire's condition is deteriorating fast. Fearing that they will soon also become infected, the others begin to argue with one another over what they should do about their situation. Claire is then quarantined in the tool shed outside. Sean later discovers rotten spots on her thighs. During this time, Claire drinks a glass of water from the river contaminated by the infected man and begins to feel ill. They soon discover that the woman was related to the hermit they killed so they leave quickly. Daryl and Bender come to a woman's house to ask for a ride into town. In the morning, a young deputy, Winston Christina (Alison Lohman), shows up at the cabin and promises Sean she'll call a tow truck. After the man exits the car, Sean sets-light to the infected man and he runs aflame back into the woods where he dies in a river. He tries to drive away in their car, but vomits blood all over the windscreen and the seats of the car.
Desperate for help, the hermit comes after the group. Later on, they hear a knocking at the door and discover it's the diseased man that Bender shot before.
However, once it starts raining, he leaves to take care of his camping equipment and the group retreats into the house. Though a little eccentric they allow him to join in when he offers them marijuana. They soon encounter a local college kid named Johnny (Noah Jupe) who approaches them with his dog, Rat. They build a bonfire and share ghost stories with each other. Scared, Bender shoots at him again in order to repel him and runs back to the cabin.
He accidentally shoots the man who discovered the rotting dog in the beginning of the film while hunting whom he mistook for a squirrel. Sean and Claire go for a swim in the river while Bender goes hunting for squirrels in the woods. When they arrive at the cabin, Daryl and Hannah immediately retire to their bedroom and have playtime. Along the way, they stop at a local convenience store for food where a young boy (Matthew Helms) outside the store bites Sean on the hand. The scene turns to five college friends, Daryl (Norman Reedus), Hannah ( Cerina Vincent), Sean (Jeremy Sumpter), Claire (Molly Ringwald), and Bender (judd Nelson) who have rented a cabin in the woods. After poking it a few times, he pulls the dog up and notices that his flesh is rotted, spurting blood on him in the process. A man ( Arie Verveen) is walking in the woods and comes upon a dog that he believes to be sleeping.