Melinda, a troubled teenage girl who is immuno-compromised as a result of the medications she must take after a heart transplant, has a severe allergic reaction and goes into shock when her boyfriend visits her. Meanwhile, House and Wilson continue to work out the problems in their new living arrangement.
While House's staff tries to diagnose a woman whose uncontrollable muscle flailing caused her to crash her car, House and Stacy try to resolve their relationship issues once and for all. Cameron refuses to take her HIV test, wary of the results.
While a severely burned teenager is admitted and his blood tests come back with strange results, House makes himself the guinea pig in his own unofficial tests of a new drug designed to treat migraines to prove a former medical school colleague is wrong about the drug.
While attending his editor's retirement party, a journalist collapses and hits his head on a desk. When he regains consciousness, his sentences are garbled and incoherent, so he is rushed to Princeton Plainsboro Teaching Hospital. With House and Stacy stranded at an airport due to bad weather, the team is forced to solve the case with House helping out over the phone.
A gay man with full-blown AIDS collapses in front of House's home and goes into shock. When House discovers the man's father is suffering from symptoms of his own, he must determine if they might be connected and save both their lives. Meanwhile, Cameron faces a potentially life-threatening disease of her own.
House and Chase find themselves in a serious situation after a young mother with stomach pains dies. Months later, Stacy counsels Chase prior to his disciplinary hearing, and must determine whether Chase made a mistake that ultimately led to the patient's death. She soon realizes he is holding something back.