A teenage couple decides to go for a drive in his dad's Porsche. The boy, named Keith, begins choking and coughing up blood. Distracted, the girl spins the car out and they are broadsided by a bus.
Cameron presents the case: the 16-year old victim of M.V.A. has been in an out of the hospital with internal bleeding for three weeks. House attributes it to the car crash, but Cameron says the bleeding started before the crash. House is more interested in getting his Vicodin prescription refilled but the pharmacy is empty. Cuddy sees House popping more Vicodin and challenges him to quit his addiction. He says he takes it to treat the pain, so she offers a month free from clinic duty if he goes a week without pills.
Cameron mentions that the victim has non-inherited hemolytic anemia, which is incredibly rare. House dismisses it as meningitis, but that's not it either. He calls his group together and tells them they have to figure out why the patient's red blood cells are supplying oxygen to the body. House instructs them to run tests for an infection, as well as Lupus, drug use and cancer.
In talking to the patient's father, Cameron learns that Keith's girlfriend was formerly in rehab and that his mother died of pancreatic cancer. The radioimmunoassay test is negative on drug use. A Gallium scan shows no infection and a radioactive isotope injected into the bloodstream shows no inflammation. The Lupus test comes up negative as well. Wilson performs a biopsy to check for lymphoma, but that too is wrong.
While the doctors mull other possibilities, Keith complains that he has something in his eye. The doctors find nothing, but Keith still can't see. Foreman observes a retinal clot. However, any treatment for the clot would kill him because of his low blood flow. They have two hours to save either his eye or his life. House asks his team how something could be causing both internal bleeding and clotting. Infection causes clotting, so what would be hiding from the Gallium scan? It must be a cardiac clot that flicks off and travels to the eye.
Chase performs an echocardiogram on Keith's heart, but begrudgingly admits that they are not going to treat his eye. The blindness will become permanent. Chase later tells House that the test showed no cardiac infection. House has him up the antibiotics. Chase thinks he can remove some liquid from the eye itself to make room for the clot to move out on its own. Chase leaves and House backs against a wall. He's in tremendous pain.
With a needle, Chase removes some vitreous humor from the eye which helps Keith see again. After the procedure, Keith's girlfriend comes in and kisses him. He vomits. The doctors rush him to the ICU. His liver is shutting down and he is dying. Keith's father is enraged. Cameron asks House if proving Cuddy wrong is worth all of this.
The team wonders what would cause liver damage. Hemolytic anemia is ruled out. House suggests hepatitis-E, even though Lupus is more likely. House thinks they need to rule out hep-E because it has no treatment, so he instructs the group to give Keith mendrol, which will react with the hep-E to make him worse. If not, they'll know that Lupus is the cause. Outside, Foreman tells Cameron that House is detoxing from Vicodin and is losing his mind. In his office, House sweats in pain.
Cameron tells Keith's father that she believes his son is afflicted with Lupus. To distract himself from the pain, House smashes himself with a paperweight and breaks a bone in his hand. As Cameron is treating him, Cuddy demands to know why House had Cameron lie. Now Keith's father wants his son either treated for Lupus or transferred. But when Cameron tells him that Keith is too weak to be moved, he relents.
Chase and Cameron prepare to begin the treatment and Keith starts to hallucinate. Cameron notices that Keith is bleeding profusely from the rectum and is going into hypovolemic shock. An angiography later reveals major internal bleeding, severe hemodynamic compromise and complete liver failure. Cameron says that hallucinations are from psychosis, which proves that Lupus is the cause. She's angry that they had to dally with hep-E because Keith needs a new liver. House still thinks Lupus is the wrong diagnosis, but he asks for Keith to be moved to the top of transplant list anyway.
In his office, House vomits from the pain. Foreman comes in with a bottle of Vicodin so that he can recover to treat Keith. Cameron and Chase break it to Keith's father that the Lupus is too advanced to treat and the transplant list has over 15,000 patients. House is still pondering who the "Jules" is that Keith yelled out during his hallucination. Keith's father informs them that Jules is their cat who died about a month ago. The girlfriend says that Jules slept in the bed with Keith.
Foreman and Chase exhume the cat. House does an autopsy. At the same time, an emergency liver comes in. Keith is taken into the OR and is prepped. Houses rushes in to stop the surgery, announcing that Keith doesn't have lupoid Hepatitis. He has acute naphthalene toxicity from termites. Termites create the toxin to protect their nests, and judging from the contents of Jules' stomach, Keith's bedroom was also infested with termites. The surgeon refuses to stop, so House spits on him to spread germs everywhere.
In the hallway, the group refuses to believe House's new diagnosis. If it was environmental, Keith would have improved in the hospital. But House explains that naphthalene is fat soluble. Keith was repulsed by the hospital food and hadn't eaten much, so his body started burning fat and the poison poured into his system. Keith's father punches House in the face. House promises that 24 hours of calorie intake will heal Keith. If they do the surgery, it won't solve anything.
Foreman and Chase hammer open a wall in Keith's home bedroom. Termites pour out. House was right. Back at the hospital, Keith is rapidly improving. And House made it through the week without any pills. He comes to the realization that he's addicted, but since he is functioning he'll just keep taking the drugs. Wilson yells at him for changing in the last few years and becoming miserable. He's using his leg and the drugs as an excuse.