Emmy Harding, a 30-year-old personal trainer, runs up the steps of an empty football stadium as she is filmed for an exercise video. She extols the virtues of hard work and no short cuts to weight loss to the heavy-set people trailing her. As she helps one of them, Emmy suddenly collapses.
At PPH, Cuddy gives House the case file on Emmy. Cuddy follows him to his office because she has to share it with him. Hers was destroyed in the hostage incident. Taub and Kutner are there waiting. Foreman is with Thirteen in the General Research Center as she begins her clinical trial for Huntington's disease. House says Emmy's normal CT means her lung problem has nothing to do with her lungs. Taub wonders if she took steroids and Kutner suggests exercise-induced asthma.
Downstairs, Thirteen sees another Huntington's patient with far worse symptoms than she has. She remembers when she was younger that her mother was similar. Foreman tests Thirteen's reflexes. Her nerves have started degenerating.
Taub and Kutner monitor Emmy as she exercises in an arm ergometry machine inside the morgue. When Kutner explains that not enough fat creates a Vitamin E deficiency that could cause nerve damage, she collapses to the floor. It is not asthma. They scan her for a tumor. Kutner tells Taub about the website he set up to give second opinions to patients. It is called "Dr. Gregory House's Second Opinion Clinic." Taub threatens to squeal unless Kutner cuts him in on the money. They notice that Emmy's stomach is only 1/8 its normal size. Taub and Kutner report to House that Emmy had gastric bypass surgery where her stomach was stapled. She then had the records pulled from her files so it wouldn't ruin her DVD sales. The surgery was done laproscopically to produce very tiny, almost imperceptible scars. House tells them to treat her like a fat girl inside.
Kutner recommends that Emmy has Sleep Apnea, which cuts off the oxygen to her brain and the resulting neurological. They go down to the GRC to consult with Foreman and Thirteen on the case. Foreman is hooking Thirteen up to an IV line. She and Kutner consider that side-effects from Emmy's gastric bypass surgery could create mal-absorption issues such as a blind loop of bowel. It ulcerates during exercise, and bacteria gets loose in the blood stream may migrate to her heart and lungs. Taub confronts Emmy about lying about the gastric bypass. He orders a stool sample from her.
Wilson joins Cuddy in her office to nudge her about House's office.
Emmy's stool sample reveals that there is high fat content, indicative of SIBO. House performs a test that disproves this. Instead, he wants Emmy checked for sleep apnea. As they test Emmy, Kutner and Taub are preoccupied with looking at CT scans of their online patient. Taub suddenly notices that Emmy's EEG is flat-lining. She has snuck out to run on a treadmill even though she has a broken ankle. She cannot feel that her leg is bleeding from the cast pressure.
House, Taub, Kutner, Thirteen, and Foreman discuss this latest development as they walk. The numbness in her left foot is ascending into her leg, and Kutner says that the alpha waves on her EEG rule sleep apnea out. They smell something rancid when they arrive at House's office. Cuddy explains that she was mixing some hydrogen sulfide for "good and valid reasons" and might have "accidentally spilled some." Foreman's pager goes off and he tells Thirteen they must go. She would rather finish diagnosing. Foreman heads back towards the elevators, annoyed.
If the problem is in Emmy's brain, it could be MS or early onset Parkinson's. Taub thinks that, if it's her nerves, it could be transverse myelitis. House orders an NCV (nerve conduction velocity) test. Taub attaches electrodes to Emmy's leg to measure the amount of time it takes for an electrical impulse to travel along nerves. She confesses to him that she is a hypocrite, but it's not about DVD sales. Emmy is helping her clients live better lives. Her arm starts to shake. Taub states that the issue is not her nerves, it is her muscles. Muscle weakness could indicate myasthenia gravis.
Thirteen is not downstairs when Foreman checks on her. Meanwhile, DeeDee, Taub and Kutner's online patient arrives at the hospital to see Dr. House. She runs her fingers through her hair and a large chunk comes right out. Seeing House, they tell DeeDee that he is gone but that they will take her to the ER.
Later, Kutner suggests to House that Emmy probably used a lot of Botox to tighten up her skin and she may have a botulinum reaction. House thinks it could be heavy metal toxicity, which can be treated with chelation. House swings a sledgehammer at Cuddy's toilet and demolishes it. Taub and Kutner just stand there, watching him.
Thirteen enters her loft to find Foreman waiting. He doesn't understand why she has followed all of the instructions but won't show up for appointments. She claims that she came down right after she finished with House but that Foreman was busy with someone else. "Show up on time tomorrow or don't show up," Foreman warns. He leaves. Thirteen has another flashback about her mother.
Emmy lies in bed, looking more pale and weak. The chelation didn't work. Her muscles are still deteriorating. The entire team is gathered, sitting on the steps of the stairwell. Thirteen throws out Coronaro-cardiac fistula and Foreman comes up with Austrian Syndrome. Kutner's pager goes off. He looks alarmed, but tries to hide it. Taub notices. So does House. Then Taub's pager goes off. Foreman agrees with Taub's theory that Guillain-BarrÃ© fits: the muscle weakness is the precursor to full paralysis. House says to start her on plasmapheresis.
Cameron, Kutner and Taub attend to DeeDee in the ER. Strangely, she won't stop singing. Kutner can't believe this is happening. When a drop of blood drips from DeeDee's ear, Cameron says he has to tell House.
Taub talks with Emmy. Her auto-antibodies are attacking the good proteins. Emmy asks when she will be able to run again. Taub explains that most people make a full recovery within four months to a year. He motions for her to stand up. She hesitates, but then slowly swings her legs over the side of the bed and stands. Emmy takes a few painful steps. He takes her arm and leads her out of the room.
Cameron, Chase and Kutner discuss DeeDee's case in the cafeteria. Chase offers to scan her for a 25% cut of the website income.
House enters Wilson's office and spreads a schematic of Cuddy's office right on top of Wilson's work. He convinced the contractor that he was Cuddy's boss and that all office renovation plans need to go through him. He is having a bidet installed instead of a toilet. Wilson tells him to just ask her out. It would cost the hospital a lot less.
Emmy dreams that her clients attack her, and she can barely breathe when she wakes. House and the team are gathered in his unfurnished office, sitting on the floor. Emmy's hallucination rules out Guillain-BarrA. Whatever this is, it's now in her brain. Thirteen heads for the door and suggests CNS lymphoma. Taub considers prion disease, and House tells him to get a brain biopsy to confirm. However, Cuddy orders Taub to rule out CNS lymphoma first, astrocytoma second, then eliminate other brain tumors. She allows him to perform a brain biopsy as a last resort. House walks up close to Cuddy and places a hand on her breast. Cuddy says nothing, gives him a look and he lets go.
Thirteen enters the waiting room and sees the other patient struggling to put on her sweater. She has another memory from childhood. Thirteen approaches her.
With Emmy's head MRI coming out clean, she does not have CNS lymphoma. Yet Taub tells her that she may have a brain tumor. Emmy asks to stop at the cafeteria for chocolate cake. He knows this means she's giving up.
The furniture is back in House's office. He sits alone, contemplative. Taub enters and asks him to get Cuddy's approval for the brain biopsy. House says he will do the biopsy himself. Taub reminds him that Cuddy wanted them to eliminate seven different things. "Cuddy doesn't always get what she wants," House answers. When he pulls open the patient room door, Emmy is stretching her legs and feeling better.
The team gathers again. House asks Taub what he gave her after the MRI. It was chocolate cake. House comes up with an actual diagnosis -- hereditary coproporphyria. The treatment is a high carbohydrate diet, rich in sugar. House and Taub enter Emmy's room with a chocolate cake. When she was heavy, she was self-medicating. Taub explains that they just have to reverse the gastric bypass and put her on a high carb, glucose-enriched diet. Emmy refuses. "Most people don't have the guts to admit they'd rather be pretty than healthy," House tells her.
Cuddy walks towards her office. Wilson hurries after her with a warning not to pursue House. She assures him that she isn't. Cuddy notices that her new desk is actually her old one from med school that her mother kept in storage. House did this for her.
Thirteen admits to Foreman that she wanted her mother to die because she yelled at her so much. She never said goodbye, and her mother died with Thirteen hating her. Foreman hugs her.
Taub and Kutner go to the ER to find DeeDee is gone. A nurse tells them she suffered respiratory arrest and died. They stare at DeeDee's corpse, speechless. House is standing behind them. House climbs on top of the corpse and starts chest compressions. DeeDee coughs, gasps for air and sits bolt upright. Taub and Kutner both jump back. DeeDee starts laughing. House hired an actress to fool them, and Cameron and Chase played along. House wants fifty percent of their website profits. DeeDee tells House that he still has three paid hours left.
Cuddy heads towards House's office but stops in her tracks when she sees House and DeeDee talking and laughing. Cuddy's face falls with disappointment.