A special education teacher named Sarah starts to bleed from her nose and mouth in her classroom. She collapses to the floor.
Cameron, filling in for Dr. Cuddy, approaches House in the cafeteria with Sarah's case. He discusses it with his team. Foreman suggests that it is a blood issue, and Thirteen thinks that a Thoracic tumor is a better fit. In front of the others, House teases them about their new relationship. He orders a bleeding time test on the patient. Thirteen and Kutner perform the test and marvel at Sarah's positive outlook. Her blood does not clot.
Wilson visits Cuddy and baby Joy at home. Cuddy confesses to him that she feels nothing for the baby.
Thirteen informs the team that clotting proteins aren't Sarah's problem. It's her platelets. Kutner brings up ITP, which means they should start her on methotrexate. House agrees and orders a total body irradiation. The team is shocked, but he says that it will stop her from bleeding into her brain. House asks Cameron for the TBI and she consents.
Sarah does not respond to methotrexate. House tells the team that Cameron allowed him to do the TBI, even though he never intended to do such a reckless, drastic procedure. Thirteen adds that they go through the motions of the procedure without really doing it. In the meantime, House prescribes double the dosage of methotrexate and prednisone.
Foreman and Chase discuss that Thirteen is on the placebo in the clinical trial. Foreman considers switching her over to the real medicine.
Sarah lies connected to a cardiac monitor. In the control room, Taub and Thirteen look at monitors. Sarah sits up because she has to urinate. As she rises from the table, she suddenly collapses with no pulse. The doctors shock her heart back to rhythm. House and the team examine DDX echocardiagram images of Sarah's heart. Thirteen wonders if the woman's own body is making a toxin, such as cold agglutinins where normal protein gets activated by cold temperatures. House instructs them to immerse Sarah in an ice bath so that the cold will activate her cold agglutinins to confirm the diagnosis.
Cuddy argues with Cameron about her decision to allow House to do the TBI. Cameron states that she had to say yes because House wanted her to say no -- there was no medical rationalization. Just then, House enters the office and takes a seat. He seems to know how Cuddy is feeling about Joy. Wilson had told him what Cuddy had confided in him about motherhood. "Legally, you haven't adopted her, no obligation, no strings, it can be undone tomorrow," House says. Cameron is appalled at his answer. She has him confirm that Sarah's blood does clump in the cold before giving her the ice bath.
"So she let you nuke the patient no problem, but makes you jump through hoops to give her a bath? Why would she do that?" Taub asks. House really doesn't know. It seems Cameron was playing him. Meanwhile, Kutner enters the patient room to find an autistic boy from the class at Sarah's bedside. Kutner offers to close the blinds so that the nurses don't ask questions.
Foreman takes a test tube of Sarah's blood and puts it in ice. He throws out the idea to Thirteen that might be on the placebo. He is gauging whether he should tell her the truth. Foreman goes to see Cameron, and she tells him to not be an idiot.
Sarah eases into an ice bath, hooked up to a cardiac monitor. Kutner attends to her. Thirteen watches the monitor, several towels and de-fib paddles at the ready. Kutner tries to keep Sarah's mind occupied, which bugs House, who is observing. Her heartbeat is normal after the three minutes. However, one of the things Sarah said about mixing up a room number stands out for House. He thinks she has a lesion in the left parahippocampal region of her brain. Foreman notes that every time a decent person comes in, House sets out to prove that they have brain damage. How else could they be so nice? Kutner also rejects House's theory. The platelet dysfunction plus cardiac arrest points toward a pancreatic tumor. House responds with a diagnosis of MS and warns that the lungs will be next. He says for them to do a brain biopsy in the parahippocampal region to find the plaques.
House and Kutner take the dispute to Cameron. She approves them to do an MRI in order to rule out the brain. Meanwhile, Cuddy enters Wilson's office with the baby because she does not want to go home. She tells him that she is considering what House advised. "He's always cold; he's always an ass; but he's rarely just... wrong," she admits.
There is no plaque on the MRI images of Sarah's brain. House tells the team to go ahead with the ERCP. Foreman hangs back. He wants advice on his dilemma with Thirteen's placebo. House asks if it is worth risking the rest of his life in medicine. That is, unless Foreman loves her.
Kutner works an endoscope down Sarah's throat. She struggles to breathe. House was right -- it is in the lungs. House tells the team that a picorna virus could cause localized demylination that an MRI wouldn't detect. A nerve conduction study on the surface of her brain will show the dead spots. This entails cutting off her skull and exposing her brain. Kutner implores that a pancreatic tumor explains the heart, the blood, and her lungs.
House comes to Cameron. He wants to find what set off the MS, like perhaps equine encephalitis. Cameron does not give her permission. "You're asking me to let you cut off the top of someone's head. I need more than â€˜I'll know it when I see it,'" she says.
Foreman and Thirteen are sent to Sarah's classroom to investigate. Thirteen declares that she wants children.
Wilson goes to Cuddy's home with a gift. It is a picture frame with photo of a teenage girl. He says that he had an age progression image of Joy made in order to show her that Joy will be a full person one day. In reality, it is the picture that comes with the frame.
House brings Cameron a lab report and a vial of fruit flies. Kutner ran his intra abdominal ultrasound and did not find any evidence. House claims that he can only get the proof he needs from inside Sarah's brain. Cameron acquiesces.
At the surgery, Kutner urges House to remove Sarah's spleen. Splenic lymphoma explains the damaged platelets, the heart, and the lungs. Sarah is still wide-awake, her head bolted into a stereotactic frame and her brain exposed. A neural net sits on the surface of her brain, composed of twelve multi-colored wires snaking out of her head and into a computer. Cameron works the computer as House pulls up a stool in front of Sarah. He asks her a series of questions designed to stimulate left brain function: logic, reason, problem solving. Kutner watches the surgery through the glass, on his cell phone with Cuddy. Suddenly, Cuddy's voice comes over the P.A. system. Cuddy holds Joy, feeding her a bottle with one hand, balancing her phone in the other. Cuddy turns to the crying baby, doing her best to hold it together. The crying sound annoys Sarah. Cuddy panics and snaps. The baby stops crying.
Post-surgery, Kutner continues to press Cameron for an immediate spleen surgery. House sits on a metal stool, away from them, lost in thought. He wonders why the baby's cry annoyed Sarah. Later, Cuddy comes to House's office with Joy. She has bonded with the baby. Cuddy offers up Joy for House to hold. Joy spits up on him. House starts a lecture about the evolution of women's hips when he has a realization about Sarah's illness.
Kutner presses the ultrasound wand around Sarah's abdomen as House enters. He takes the wand over her heart. "In the womb, blood has to bypass the lungs since they don't work yet," he explains. "When we're born, we take our first big breath; lungs expand and the ductus closes. Yours didn't." House views the patient's ductus arteriosis on the monitor. When she gets stressed, Sarah's blood pressure goes up which forces the ductus wide open. Her blood takes a little detour to the right brain and stays away from the left. This means that when she gets stressed, she actually becomes un-stressed. This is how she has the patience to work with children that would annoy others.
Cameron is with Cuddy in the nursery. She wants to quit because she knows she would always say yes to House's demands.
House watches Sarah in her room as she is visited by one of her students. He becomes annoyed and walks away.
Foreman has several IV bags in the refrigerator in his office. He takes one out, puts a new label over it -- for Thirteen. She passes by. Foreman nods for her to come in.
As Cuddy is getting ready for work the next morning, she must force herself to turn away as Joy begins to cry. Cuddy's nanny picks up the baby to calm it. Cuddy fights back her own tears.