Famous celebrity photographer Emma Sloan is five months pregnant. She arrives late for a shoot with a band member from All-American Rejects. She complains that the words on the backdrop are jumbled even though they are correct. Emma panics and shouts for somebody to call 911 because she's having a stroke.
House ambles into Emma's hospital room with a quick order to hold her arms out with palms up. Her right arm begins to droop. House asks if her ob gyn cleared her and her fetus. Emma affirms this and House calls him an idiot for missing the pronator drift. House examines Emma's eyes and notices an issue with vessels. He thinks her microaneurysm is a predictor of future strokes. In the conversation, House learns that Emma was artificially inseminated with a donation from a gay neurologist. He also notices that Emma's catheter bag is half-filled with blood.
The team later reports that a urinalysis revealed that there was excessive protein and red blood cells. A chem panel showed a creatinine level over 2.5. After the stroke, Emma's kidneys have been shutting down. Cameron wonders if the kidney problem came first and threw off a clot that caused the stroke. House thinks the heart is much more likely to throw off a clot and mentions the six cases of strep in Emma's history. Untreated strep leads to Rheumatic fever, which leads to mitral valve stenosis, which leads to the team exiting the office to go check Emma's heart.
While Emma lays in a CT scanner, Chase and Cameron discuss House catching them in the supply closet. Chase doesn't think it's a big deal, but Cameron worries that House has some secret plan in the works. Chase wonders if Cameron is simply annoyed that House caught them and doesn't care. He then notices a calcified mitral valve in Emma's heart.
Emma is put in surgery so that Chase and Cameron can insert a balloon into her narrowed valve. They believe this will solve her problems as long as she finishes her prescribed antibiotics the next time she gets strep. But before they start, Cuddy enters. With a smile, she starts giving Cameron and Chase orders on how to approach the procedure they've done numerous times in the past.
The team finds House in his office making vacation plans with a direct flight to Phnom Penh. They tell him about Cuddy, which House brushes off. They go on to explain that Emma's kidneys are still failing. House figures that means they screwed up the procedure, but Cameron counters that maybe House screwed up the diagnosis. Considering the pregnancy, the doctors mention pre-eclampsia, proteinuria, low platelets. They also bring up hypoperfusion, a condition in which a fetus acts like a parasite and steals crucial nutrients and blood from the mother. Foreman, mentioning the pregnancy could be irrelevant, wonders about sepsis or HUS/TTP. House sends them off to check for everything.
All of Emma's tests come back clean. The doctors are baffled. Everything that screws with the kidneys is something they considered. House approaches Emma and informs her that they've eliminated all possibilities for her body. But the other body -- the fetus -- isn't performing so well.
House convenes his team in the office and explains Maternal Mirror Syndrome to them. In short, the creation of a new system inside a functioning body goes wrong. As the fetus slowly dies, rather than miscarry or become a stillbirth, it kills the mother's body as well. The good news is if they fix the fetus, Emma will get better. The bad news is that this syndrome rarely turns out favorably. House suggests they start with a look at the fetus's heart. Unfortunately, it's nearly impossible to get an accurate scan on a fetal heart because the fetus doesn't stop moving. Yet House has a solution. He's going to paralyze the fetus.
Cuddy catches wind of this scheme and tries to stop House. House is quickly able to talk her into it. And together, they're able to talk Emma into the procedure. Everything is a success and the fetal heart is structurally sound according to the MRI. However, the bladder is four times the normal size. It's so engorged that it's squeezing out the other organs, not allowing space for the lungs to develop. Cuddy informs Cameron that it's a lower urinary tract obstruction that can be fixed by inserting a shunt. Cameron asks if Cuddy is taking over this case, and Cuddy replies that House won't care now that the diagnosis is in. Cuddy then warns Cameron that dating Chase can only end in one of two ways: marriage and happiness, or a breakup that leads to Cuddy having to fire one of them because they can no longer work together. Cameron knows that House told Cuddy about them.
Cuddy informs Emma of their plan to insert the shunt, which should solve the problems. They will have to check the fetal kidneys first to make sure they function properly. If they're too damaged, there's nothing the doctors can do.
Cuddy finds House in her office. He happily explains to her that her kidney test will be inconclusive. The urine is stale, and she'll need to do at least three kidney taps before she can find fresh urine. Then he asks Cuddy why she's so interested in this case. Perhaps Emma is basically Cuddy, a single woman in her 40s who is using in vitro. He wonders whether Cuddy wants Emma to succeed to give herself some hope. Cuddy thinks on this, and agrees. She gives the case back to House.
Chase breaks the news to Emma that the fetus's kidneys aren't damaged. They're going to insert the shunt and everything should turn around. Surgery for the shunt is a success and the fetal bladder starts to decompress. Emma complains of abdominal pain and when Cameron checks her eyes, they're yellow. Cameron and Chase let House know that Emma's liver is now failing. House begins to wonder what the fetus is hiding. Maternal Mirror Syndrome has one surefire cure: delivery. However, a fetus isn't viable at 21 weeks. Who gets to tell Emma?
Emma asks about putting the fetus on ventilators, but the fetus is at least two weeks away from being viable. The catch is, her liver isn't going to last two more days. Emma refuses an abortion, so House points out that either the fetus dies or they both die. There is no chance of her dying and the baby surviving. Emma declares she won't consent to an abortion and tells House he has two days to figure it out.
House wants Cuddy to order an abortion, but Cuddy refuses. He claims the fetus is nothing more than a parasite at this point, but Cuddy says they need to exhaust every avenue before aborting. Cuddy gathers the team to run a differential, asking if their original assumption could be wrong. Desperate for a possible solution, Cuddy asks if the liver problems could have developed after they cured the urinary blockage. Cameron and Chase mention acute fatty liver, viral hepatitis and HELLP Syndrome as possible causes. Foreman points out that Emma's platelets are too low. If they biopsy the liver, they won't be able to stop the bleeding. Cuddy mentions transjugular hepatic biopsy. If they go into the liver from above and it does start to bleed, then the blood will go right back into her veins. Impressed, the team heads out.
Chase and Foreman thread a needle through Emma's veins. When they pierce the liver, her heart rate and blood pressure spike. The fetal heart rate explodes to 185 and contractions begin pre-term labor. Later, the doctors tell Cuddy they were able to control the pre-term labor with tocolytics. But the liver biopsy was negative, which means it is definitely Mirror Syndrome. The doctors insist that there's no solution outside of termination. Cuddy suggests overloading the fetus with corticosteroids in an effort to speed up the lung development. Then they can look at the lungs in search of a problem. The doctors rattle off a long list of developmental and practical problems a corticosteroid bath would create, but Cuddy is undeterred. She rushes out to perform it herself.
During the procedure, Emma develops a pulmonary edema, just as the doctors predicted. Wilson enters at the behest of the team. He also advises termination. All Cuddy has done is turn Emma into an incubator for a dead fetus. Cuddy tells Wilson to get out.
The next morning, Cuddy shuffles into Wilson's office with an admission that they were all right. Emma is getting worse faster than the baby is getting better. Cuddy asks Wilson what House would do in this situation. Suddenly, she has a revelation. Since Emma is already on a respirator, it doesn't matter what Cuddy does to her lungs and she can actually increase the corticosteroids. It also sounds like a risky flight of fancy that House would attempt.
The gamble works and Cuddy gets a viable MRI of the fetus' lungs, which she rushes over to House's apartment. The MRI presents many possibilities. House blows off his airport cab for vacation and returns to the hospital. The problem facing the team is that all of the normal lung tests -- transesophageal echo, high-res CT scan, ventilation perfusion -- are impossible to perform on a fetus. Frustrated, Chase blurts out that what they would normally do if stuck is perform exploratory surgery. House thinks that sounds like a good idea.
House plans to open the uterus, then open the fetus itself to take a look around. Despite Cuddy's warning that this procedure is incredibly dangerous, Emma sees a real-time 4D scan of her fetus and emotionally consents. The observation deck is packed for the surgery. When House cuts into the uterus, the fetus's arm emerges, tenderly grabbing House's finger. House freezes, staring at the tiny hand in awe. Despite his earlier insistence that this is a fetus and not a baby, he seems moved by the moment.
Later in the surgery, the fetal surgeon spots three lesions in the lungs and pronounces it to be C-CAM. He thinks he can reset them. Suddenly, Emma begins to crash. Cuddy tries to shock her back to life. House declares that the surgery isn't crashing Emma. It's the fetus. He grabs a pair of scissors and heads to the womb. Cuddy orders him to step back or get electrocuted. House continues working, but sees Cuddy isn't bluffing. He jumps back right before she delivers another shock. Finally, Emma's heart rate returns to normal.
The surgery is a success. House performs a follow up exam on Emma and everything is just fine. Emma thanks him, but House admits that the pregnancy would've been terminated if he had his way.