At a fundraiser for his Presidential run, Senator Gary Wright is overcome by illness and collapses. At the clinic, Volger asks House to give a speech at a pharmaceutical meeting and offers to relieve House of staff-firing duties if he does so. House also has to examine Wright and believes something is up when he shows a lack of reflex. After brain biopsy, the tests prove negative for a brain tumor but shows a lesion caused by toxiplasmosis – indicative of AIDS.
Wright denies the possibility and refuses to take the pills for treatment, then calls for anonymous testing for AIDS and regular tests for cancer as "cover." The AIDS test on Wright proves positive and when House tries to get a list of Wright's sexual partners, he still claims he couldn't have gotten it from sex. Later Wright's legs go out and House concludes the AIDS test was a false indicator – a second test proves he doesn't have AIDS but he's dying of something else.
Wright's muscular condition continues to deteriorate. He has her go into a sleep lab while they run more tests on the senator. One shows he has several enlarged lymph nodes but nothing definitive. It's suspected Wright has leukemia of the spleen, which may cause his death if they run another biopsy. Before they can run the test, Wright goes into respiratory distress so they cannot do the biopsy.
Wright tests negative for leukemia but positive for Epstein-Barr, then takes Wright off the respirator. He concludes that Wright did not have a childhood accident that led to a scarred tongue, but that he suffers from epilepsy. The drug he took, in combination with Epstein-Barr, causes weakening of the antibodies. They give him the proper treatment and he shows rapidly recovery.