Cuddy takes her mother Arlene and sister Julia with her to buy dresses. As they talk, Arlene complains that her heart is giving her problems. Cuddy dismisses her as just complaining at first, but then checks her pulse and says they need to get her to the hospital.
House is hiding out in the morgue and Masters wonders why. Cuddy arrives and says that Arlene needs House, but he insists that her mother is just psyching herself into an ailment. He warns that Cuddy knows how he operates and it won't go well, but she insist. House puts on a lab coat and tests her, and tells her that the problem will resolve itself. Arlene asks if it's related to her other symptoms, but isn't sure which symptom and suggests they read the last 15 years of her files. She won't take no for an answer, and House starts to lose it. Cuddy interrupts and assures Arlene that they'll do a full series of tests.
Taub and Masters check out Arlene's house, and Taub insists that there is no case. He finds photos of Arlene with a muscular Hispanic sexual partner, and pills of Azracon. They give the pills to House, who explains to Cuddy that Azracon is a Mexican herbal treatment for stomach pain that contains lead. She is relieved, but House notes that they found photos of her with a contractor named Jesus. Much to his surprise, Cuddy is impressed rather than shocked. While she administers chelation for the lead poisoning, Cuddy asks Arlene why she's taking the Azracon, and Arlene admits that her boyfriend recommended it. Julia knows all about it, and Cuddy wonders why Arlene didn't tell her. Cuddy is shocked, and Arlene is surprised that she's shocked.
Foreman arrives at his apartment, where Taub is moving in with him. Rachel arrives to drop off Taub's mail, and says that they have to move on. He wonders who she's moving on with, but she refuses to talk about it and offers him a job as a part-time medical consultant with her brother, Jamie. Taub points out that Jamie broke his nose when his brother-in-law found out that he was cheating with his partner's wife. Rachel just gives Taub her brother's card and leaves.
House goes to see Arlene after she sends him multiple emails and text messages. She notes that she's been checking lead poisoning symptoms on the Internet, and her symptoms match. House admits that he believes she's a hypochondriac, and gave her a placebo to see how she'd react. Arlene responds by firing him. After some struggling, Cuddy convinces her mother to stay at the hospital but to be treated by Dr. Kaufman in Internal Medicine. House insists that he did the right thing, but Cuddy doesn't believe it. They're interrupted when Kaufman calls to tell Cuddy that Arlene is at A-Fib at 170. As Cuddy goes, she tells House that he's still on the case, but Arlene can't know about it.
The next day, House meets with Kaufman and tells him to give him all of the information. Kaufman refuses, noting that Arlene requested that House be kept out of the case. Further, he figures that House will eventually cut him out of the case entirely and end up putting him before the M&M board. House then bugs Arlene's room and listens in with his team. Masters objects, and Chase focuses on the case, suggesting leukemia. House admits that it sounds good, but admits that Kaufman came up with the same thing. He tells Masters to go to Admitting and find a new case for the team. However, once she leaves, House gets back to the others and now that they know Masters is still ethical, they can do the real differential. He suggest that Arlene is an alcoholic, noting that she wasn't surprised when she blacked out due to alcohol consumption during her dinner with House. He wants them to slip her thiamine pills to treat. Foreman says they have to run it by Cuddy, and House admits that's why he's in a bad mood.
House tells Cuddy his theory and already has the thiamine vitamin pills in a bottle marked antacid. They can give them to Arlene without disrupting Kaufman's biopsy. Cuddy wants to tell her mother what they suspect, but House warns that Arlene will just continue to deny. In response, she insists that she and Arlene have a truthful relationship since Cuddy's father died. However, House warns that addicts lie. Cuddy contemplates the pills, and then picks them up and goes to Arlene's room. She asks flat-out how much Arlene has been drinking, and Arlene insists that she isn't a drunk. Cuddy says she accepts that… and then gives her the disguised thiamine pills.
Later, House finds Cuddy in the lobby. She asks House to do what he has to the next time something like that comes up, and that she can't handle treating family. Cuddy tells House that he was right as usual and walks away.
Taub meets with Jamie, who apologizes for hitting him. He offers Taub one case as a tryout, and if it works out, he'll make $50,000 a year. Taub immediately accepts, and then notices that a brain-scan of one of Jamie's clients has a micro-bleed. Jamie explains that the client was hit by a pizza-delivery truck, and that no one has noticed the micro-bleed. He refuses to hear any doubt that could undermine his multi-million-dollar case and tells Taub to drop it, and Taub agrees.
As House leaves for the night, Cuddy tells him that Arlene is running a fever and House was wrong. Kaufman has rushed the biopsies, and confirmed that Arlene doesn't have leukemia. House calls the team into a coma patient's room to run DDX on him. Foreman concludes it's an overdose, but Masters suggest something more interesting. House stays silent to test them, and she starts testing the patient. Outside, House meets with the others again to run differential on Arlene. They hide out in a procedure room and House explains that Kaufman believes it's auto-immune. They suspect endocarditis, but the treatment for auto-immune could kill her if that's what Arlene has. Kaufman has already heard the theory and doesn't believe it, so House says they need to switch her med for prednisone. Foreman objects, warning that it's too risky and unethical. He refuses to go to jail to save Arlene, and says that House is losing control because it's Cuddy's mother. Chase asks if House has run it by Cuddy, and he says that Cuddy told him to keep her out of the loop. He tells them to do it or they're fired. Once House leaves, Foreman says they need to stick together and oppose him. Chase says that he believes that it's endocarditis and starts filling out the prescription for the prednisone.
Foreman and Taub go to the conference room, and Taub wonders if he's doing the right thing. He's also worried about what he saw in Jamie's office, but Foreman warns him that it's none of his business and could cost him the consulting job. Chase returns and admits that Julia knows him from a charity event, and Foreman confirms that she met him at the same event. That leaves Taub as the only person who can give administer the prednisone without Arlene and Julia realizing that House is involved. Taub says he can't, and then gets a call from Jamie asking him to check out a new case. He insists that he needs the job and ditches them, much to Foreman's disgust.
Taub goes to see Timothy, the boy who was hit by the truck. He tells the boy's mother, Kara, that her son has a micro-bleed and could die of a brain hemorrhage. Taub insists that she take Timothy to get an angiogram, and she quickly agrees.
When House discovers that his team didn't give Arlene the treatment, he warns that the longer they take, the more at risk she is. He tells them to wait until Julia is out of the room and Arlene doses off, and then make the switch.
Masters goes to Cuddy and says that she suspects that House is distracting her, and she's checked to confirm that House is preparing to give Arlene an illicit treatment. Cuddy calls House and objects to his illegal and life-threatening treatment. He points out that she doesn't want to make the tough decisions, and Cuddy asks if he's sure that it's endocarditis. House admits that nothing is sure but it's the best they have, and asks her to slip the prednisone to Arlene.
As Cuddy secretly switches the prednisone for the auto-immune treatment, Arlene notes that Julia has left to be with her family, and Cuddy points out that she's always been tougher on her than Julia. Her mother insists that she loves them both, but admits that she has more in common with Julia and likes her more than Cuddy. Cuddy turns and walks away without saying a word.
When Taub returns to the apartment, Foreman tells him that angiogram shows that the aberration on the scan was a bone in proximity to a blood vessel. There was nothing wrong with Timothy.
Arlene has an allergic reaction and Kaufman doesn't understand why. When Cuddy finds out, she calls House and the others into her office and tells them that she's secretly put Arlene back on prednisone. However, now Kaufman suspects endocarditis, so he plans to put Arlene on prednisone. House figures that it's fungal endocarditis and they need to switch to amphotericin B. Foreman warns that they're putting Arlene at risk by prescribing behind Kaufman's back, and the poison is dangerous. Cuddy refuses to take the risk, and House angrily points out that she shouldn't have let Arlene fire him. Foreman, Taub, and Chase all warn Cuddy against it, and she tells them to go. House insists that he's right, and Cuddy says she'll do it... and Masters comes in and overhears them. She agrees that fungal endocarditis fits, but insists that they have to tell Arlene because the patient is the highest priority. House tells Cuddy to leave and then tells Masters that if she tells anyone, he'll get her thrown out of med school and destroy her career. Masters tells him that lying about her won't work because everyone knows House's reputation. He agrees, but points out that buried in the coma patient's file was a form forbidding treatment without the relative's consent. She drew blood, meaning she committed a criminal assault. House kept silent, so it's all on her. Masters realizes that he set her up, and House says that he's doing it because the patient is the highest priority.
Masters runs into the bathroom and vomits.
Taub is in the restroom when Jamie comes in and slams his head into the fixture. He tells his brother-in-law that Kara reported him to the bar for hiding the facts, and scuttled the settlement. Jamie plans to sue Taub for slander and everything else he can do to destroy him, and tells him that Rachel sent a message for Taub to stay out of her life.
Masters comes to see Kaufman and says that she needs to speak to Kaufman and Arlene alone. Later, Kaufman confronts House and threatens to report him to the board. Arlene fires all of them and asks for a transfer. She accuses her daughter of lying to her, and says she doesn't care what she thinks anymore. Cuddy goes to get the ambulance.
Later, Cuddy goes to see House in her office, and he points out that she just killed Arlene. He notes that Cuddy kept him on the case despite Arlene's wishes, and that she can't control her. House points out that Cuddy has avoided confronting Arlene every step of the way, and it pisses him off. He warns that if Arlene leaves, she dies, and Cuddy will eventually blame him. House tells Cuddy to get him her patient back.
Cuddy goes to the ambulance and orders Julia out, and then tells Arlene that she sees ambition and brains in Cuddy, and rode her to make sure she could accomplish everything possible. Arlene comes to see her in the clinic because she trusts her judgment, so Cuddy tells her that if she transfers, she'll be treated nicely and die. If she stays there, House will treat her badly and save her. Cuddy refuses to let Arlene leave.
The staff bring Arlene back in, and she comments that House can't be that great if he can't run a department. He points out that he was being sarcastic, and then tests her with a sarcastic comment. Arlene is unable to recognize that she's being sarcastic, which means CNS involvement. Arlene's heart accelerates and House tries to put it all together. He realizes that she has lead poisoning and never got over it despite the fact they ordered chelation, because she's still being exposed. He cuts open her thigh and reveals that she has metallosis. Arlene has cobalt poisoning from a worn-out hip joint. House gets her to OR for more chelation treatment.
Taub is sitting in his room when Rachel comes in. She explains that Foreman called her, and explains that she didn't know that Taub believed Timothy had a micro-bleed. Rachel promises to kill Jamie if he messes with Taub again, and tells him that even though he was a crappy husband, he's a good person. She hugs him.
Masters is packing when House comes to see her and tells her that she's not fired. He admits that he's impressed that she stood by her principles. House says that he needs Masters to keep him from doing things that Cuddy won't because now she's protecting her boyfriend as well as her doctor. Masters starts unpacking.
Cuddy comes in as Arlene tells Julia that she's keeping the removed joint as a trophy. Arlene then points out that lead poisoning matched her symptoms just like she said, and takes Cuddy's hand.