Thirteen hooks up with a woman in a one-night stand. Afterwards, the woman suffers a seizure. Thirteen accompanies her to the PPH ER. Cameron asks what the patient's name is, but Thirteen doesn't even know.
Cameron presents the case to House. Spencer is 26 and suffered a tonic clonic seizure. She has a history of fatigue, and two years ago had a retinal vein occlusion. House ignores her and goes to Wilson's office, finding Wilson lying on the floor after falling over from his chair. House pulled a practical joke by removing one of the wheels. Wilson says he was resigning from his new job. House gives him a donut as a welcome back gift.
House returns to Cameron and she picks up where she left off on the patient. She suggests that the seizure could be the result of dehydration or something neurological. House thinks it is the traces of ecstasy found in her system. Cameron mentions that Thirteen said the patient took the drugs about five hours before the seizure. House becomes intrigued at the thought of the two women together.
As Foreman and the team go through the case file, Thirteen laments that her private life is on display. Foreman asks if she was also taking drugs. She refuses to answer. Taub reports that the patient had eye hemorrhaging two years ago. Kutner thinks that blood clots could explain everything, but Thirteen dismisses Spencer as a hypochondriac.
As Thirteen prepares to draw bone marrow from Spencer, House watches their awkward interaction with amusement. The patient reacts in stiffening in pain as Thirteen pushes the biopsy needle into her hip. He chats with her about their sexual experience.
House asks Lucas to investigate Wilson because he ate the donut. Wilson claimed he had a morning meeting at Mickey's Diner. No way had he come to work wanting more carbs. He lied, and House needs to know why.
Thirteen angrily tells Spencer that she found the letters she wrote trying to get House to take on her case. She accuses Spencer of sleeping with her to get to House, and Spencer admits she followed Thirteen to a bar to ask for help. Suddenly, Spencer clutches her chest and the cardiac monitor beeps.
House gathers the team. He thinks drugs would explain everything because they can mess up the electrical pathways in the heart and cause blood clots. The patient's father had bypass surgery, which makes her a candidate for atherosclerosis. She should have an ultrasound.
At Thirteen's house, Foreman tries to open the front door with a lock pick. Hovering over him, House takes out a key and unlocks it. Foreman grabs the purse sitting on the coffee table. House pulls an asthma inhaler from the night table. Back at the hospital, they show the team a spider found in Thirteen's apartment. Its venom can cause seizures and heart problems. The inhaler shows that Thirteen had asthma as a child.
Thirteen checks Spencer's body for spider bites. She shows House the lab results, which confirm low potassium. This explains the hip numbness, heart problem and a symptom of a kidney problem. Thirteen diagnoses Renal Tubular Acidosis. If kidneys don't filter acid out of the blood then the excess acid drives down potassium and causes kidney calcifications. If so, then House says all she needs is sodium bicarbonate for the acid and surgery to remove the calcifications. He tells Thirteen to catscan her kidneys.
From their parked car, House and Lucas spy on Wilson playing a video game in his house. Then they spot a sexy woman heading up the stairs. She's dressed in a very short skirt, very high heels and very low top.
Taub assists as Chase guides a small tube through a small incision in the patient's abdomen. The CT shows one more calcification near the superior pyramid of the left kidney. Foreman approaches Thirteen as she observes the surgery. "That thing you were hoping House didn't find at your place?" he says, handing her an envelope. She puts it in her pocket without looking at it. "You did the CAG test two weeks ago," he adds. "Number this high means you have less time than you thought; understandable that you'd be upset; doesn't mean you have to self-destruct."
Chase finishes removing the tube from Spencer's abdomen. As Taub prepares to suture, Spencer stops breathing. Later, Taub updates the team. Thirteen is conspicuously absent, much to House's irritation. Taub explains that the breathing problems started after they fixed her kidney problem so the RTA isn't the underlying cause. House says that the only way to find out if her airway failed is to make it happen again. He orders a methacholine challenge for the patient.
Thirteen lies on an exam table. She looks exhausted and disheveled, giving herself a bag of fluids to combat her hangover. Thirteen bolts up as best she can, yanks the IV out of her arm, but can't do much more before the door swings open. It's Cuddy.
Foreman tells House he knows that he had him investigated. House notes that he has not done anything stupid, spontaneous, or even vaguely interesting since age seventeen. House enters Cuddy's office to find a tired and rundown Thirteen. Cuddy wants her to take a drug test. Thirteen resists and House denies permission to Cuddy.
House lets Thirteen know that Spencer's surgery was not routine because she had stopped breathing. Thirteen missed a differential, and he fires her.
Wilson is at his desk watching House walk across the room without saying anything. He confides to House that he is dating an ex-prostitute. House tries to mask his distain.
Thirteen studies Spencer's chest x-rays. Foreman apologizes to her, saying they ruled out hypertension. Spencer is now on a treadmill running a methacholine challenge. Thirteen realizes that lung cysts wouldn't show up on an x-ray. The treadmill test won't close her airway and her lungs could explode. Thirteen rushes in to find Spencer on the floor. She stabs a syringe into the patient, and air escapes from Spencer's chest, allowing her lung to expand. Kutner, Taub, Foreman and Thirteen report this to House. He tells them to biopsy the cysts. The team encourages House to bring Thirteen back. House insists to Thirteen she is still unwelcome.
Lucas and House sit on a bench mulling over Wilson's ex-prostitute. Taub approaches, carrying results from the lung biopsy. House then goes to Thirteen with the results. "I know what it's like to get this news," she says. "And no one should have to get it from you."
Thirteen explains the diagnosis to Spencer. She has a disease called LAM. Surgery can remove the cysts, but the cysts replace healthy lung tissue until the lungs stop working. Spencer drops her head, stunned by this turn.
Chase and his surgical team remove the cysts from Spencer's lungs. Later, as she lies in recovery, Thirteen tells her what to expect when coping with a fatal condition. Spencer realizes that Thirteen is talking about herself. Thirteen notices blood spreading across the stitches. She gathers the team. They can't stop the bleeding. Thirteen thinks it is a new symptom: aplastic anemia.
Spencer lies in bed, pale and weak. Thirteen is in the bed beside her. Thirteen looks at Spencer, then leans in and kisses her. House knocks on the glass, motioning for Thirteen to join him. House wants a bone marrow transplant and tells Thirteen to get the consent.
Lucas is waiting for House in his office. He puts Wilson's trash bag on House's desk. There is a bag of drug paraphernalia. House smiles and rushes to bust Wilson. Yet Wilson has tricked House. "Best thirty dollars I've ever spent," he says. House still wants to know where he was the other morning.
Thirteen is waiting in House's office, and tells him that Spencer agreed to the transplant. House admonishes her. "You're gonna keep spiraling, keep screwing around, keep slashing away at every person who tries to help until no one tries to help anymore. Until you hit bottom; until you're dead," he says. He asks her back. House notices that Thirteen's lips are cracked. He is struck with an idea, and asks if Spencer cried when told she was going to die. Thirteen does not think so.
House cuts an onion on Spencer's tray table, right beneath her face. Thirteen watches from the other side of the bed. Spencer's eyes are dry. She has no tears. House diagnoses her with Sjogren's, which attacks the glands that produce tears and saliva. It also causes lung cysts and RTA. Her lack of spit makes her mouth a breeding ground for a fungus like Candida. Thirteen's asthma inhaler wiped out her mouth's immune system as well. Spencer will live. House prescribes Methylprednisolone for the Sjogren's.
Foreman checks on Thirteen. She tells him she feels alone.
Wilson enters a baby store to find Cuddy there, checking out a crib. House follows. Cuddy announces to House that has been approved to adopt a baby. She asked Wilson to be a character reference the other morning. House is shocked.
Thirteen returns back to her downward spiral, hooking up with a new one-night stand.