Cuddy walks into the Biopsy Lair and finds some lab tech working on Megan's lump. Cuddy is furious; her memo specifically told everyone at PPTH not to do anything for any of House's patients, which is not at all irresponsible or in any way endangering patient health. The lab tech says she got Cuddy's second memo ordering everyone to ignore her first memo. Cuddy never issued such a memo. I wonder if it was signed "Cuddy, who used to be a man hahahaha." She's curious as to what the tech discovered, though. It's a whole bunch of tumors.
"Not exactly," Cuddy explains to Ben and Sally Field. They're eosinophilic granulomas, not tumors. You get them from an allergic reaction, but they have no idea what Megan could possibly be allergic to. The only thing it could be is the medication they're giving her, but Megan took that medication for strep throat just two months ago and had no allergic reaction. Sally Field is starting to realize that PPTH is a hellhole of sickness and despair. Megan was better off under that building.
House is also puzzled. He stares at his Whiteboard, but it doesn't tell him anything.
Wilson goes to check on his old guy patient, only to find the sarcastic nurse sleeping in his bed. Realization spreads across Wilson's face.
"You stole my patient!" he yells at House, interrupting his non-train of non-thought. House says he won't give Wilson his patient back until Wilson gives back his guitar, who, by the way, is a female, since House ain't no homo. Wilson says there's a big difference between stealing a guitar and stealing a person, but he's talking to the wrong guy here. As far as House is concerned, guitars and people are of equal value. If anything, guitars are worth more. House assures Wilson that his abducted patient is safe, but Wilson yells that if the nurses give him the wrong meds, "Who knows what's gonna happen?!" And now it's House's face's turn to have realization spread across it. He tells Wilson where to find the old guy on his way to Megan's room.
House throws a file on Megan's bed and gives her some amphetamines to wake her up. While they wait, he says that her allergic reaction can't be explained unless the chart is lying. In Season Four, even nonliving objects lie. House asks about a woman named Liz Masters, the co-worker of Megan's who died the other day. Liz Masters, according to her chart, was on MAOIs and the pill, had an abortion last month, and is allergic to the drug they were giving Megan that she can't possibly be allergic to today. And by "Megan," he means "Liz." We flash back to the scene before the collapse, when Megan gave Liz a piece of paper. Liz looks a lot like Megan. Ever more so when her face is all swollen from injuries. The family members incorrectly identified the women, and no one thought to second-guess them. Ben, of course, won't believe it. Sally Field is starting to. The amphetamines wake Liz up, and House asks her for her name. "Liz," she gasps. Sally Field and Ben are understandably upset. House tells Ben that the good news is that Megan never lied to him. The bad news is that she never will lie to him again, since she's dead. And Liz, the depressed alcoholic baby-hater, gets to live another day. Just so we aren't completely destroyed by all the sadness, Liz's boyfriend enters the room later and is happy. And then Ben and Sally Field visit Megan in the morgue.