While a hustler is running a three-card monte game, his shill Lupe, gets confused and blows the game for him. Lupe collapses to the ground. Much later, Lupe explains to Foreman that she felt like she couldn't move inside her head. Foreman says she had an abulia, or the inability to make a decision or exercise will. This is part of a bigger issue called Transient Ischemic Attack. The blood was cut off to a section of Lupe's frontal lobe. She claims she has no drug use, so toxins might be another explanation.
The team argues about possible causes, but Foreman is adamant that Lupe is a drug-abusing scam artist. Chase thinks it is toxins. Yet her tox screen comes out clean. House is more interested in why Wilson was talking to his second ex-wife. Wilson says that she merely asked him to start looking after their dog. House then confesses that he asked Cuddy out to a play. He was only testing her. She said she was busy, but then why did she say yes to Wilson earlier?
Foreman's dad, Rodney, waits in the hospital for his son. He wants Foreman to come to his mother's upcoming 60th birthday party. She should see him while she still knows who he is.
Chase and Foreman go to Lupe's apartment for an environmental check. Chase finds a number of possible toxic causes in the apartment, but Foreman sees a crack pipe, which seemingly gives him the stronger argument. Chase says he will do the tests on the pipe so that Foreman can visit his family, something he doesn't really want to do.
Foreman tracks down his family at a nearby hotel and his mother is thrilled to see him. As she talks to him about the past, symptoms of her Alzheimer's come rushing to the fore.
Later, Foreman confronts Lupe about the pipe but she denies that it's hers. He advises her to warn whomever it belongs to that they have arsenic poisoning. Lupe starts hacking with a cough and then spits up blood on Foreman's jacket. She begins choking on the blood that's filling her throat.
Chase and Cameron run a CT scan on Lupe after a hair test only shows trace amounts of arsenic in her system. The scan reveals a mass just outside the lingual. A biopsy later shows white blood cells in the walls of the blood vessels, which isn't normal. Figuring this has to be some sort of autoimmune issue, Foreman is ready to start a treatment of steroids. House wants to know exactly what autoimmune disease it is. In the meantime, they are to begin the steroids.
Foreman checks up on Lupe, dismissing her explanations about a one-time drug use. She realizes he doesn't like her, then accuses him of being like someone who quit drinking or lost a lot of weight and looks down on those who can't. Just because he got out of the projects, he thinks anybody who hasn't is weak and stupid. Throughout this speech, Lupe struggles with a cough. Foreman studies her eyes, noticing yellow in the sclera.
Foreman reports back to the team that Lupe's liver is failing. It's not an autoimmune disease. He suspects lymphomatoid granulomatosis, which is incredibly rare even by their standards. He suggests that they start total body radiation immediately to fight the rapid spread of the cancer. House instructs Foreman to get her consent in order to begin the process. Foreman explains that Lupe doesn't like him so much. House jumps up to get the consent. If she doesn't like Foreman then he is dying to know why.
When House asks about Foreman, Lupe complains that he thinks he is better than he is. After explaining the myriad possible side effects, House hands Lupe the consent form. She freezes, and falls under another attack. House calls in the nurses, instructing them to have Lupe sign the consent form when she comes out of the attack.
Cameron and Foreman check up on Lupe after the radiology. Foreman detects a heart murmur, which is a bad sign. Cameron tightens the cuff on Lupe's arm to check her blood pressure and Lupe begins screaming in agony. After receiving news of this latest development, House realizes just how much trouble they're in.
Foreman asks Wilson for advice on how to break a terminal diagnosis to patient. Wilson tells him to be honest and to be there when the patient needs support. Foreman slides in Lupe's room and flatly informs her that she's dying. He estimates less than 24 hours to live. She came into a hospital with an infection and they didn't catch it. The radiation is the worst thing they could've possibly done because it destroyed her immune system, allowing the infection to spread to her heart. Now, there's nothing that can be done. Lupe angrily tells him to get out.
Foreman tracks down House in the ICU and declares that he is wasting their time and causing Lupe more pain. House counters that he needs to know what they missed. They have Lupe wheeled back into a private room. Foreman apologizes to her, but admits that he doesn't expect her forgiveness. When he learns that she has no close family or friends, he sits down to spend the night in her room.
When Lupe wakes up the next morning, Foreman confesses that she was right. He did have a problem with her at first. But she was also wrong. He explains that he had a rough past but received another chance. He still feels like someone will send him back from where he came if he's not always the smartest person in the room. He put distance between himself and Lupe only because he knows there isn't any.
With Foreman still at her bedside, Lupe falls into a coma and her vitals flat line. Foreman calmly switches off the monitoring equipment and notes the time. He calls in the time of death to House, who readies himself for an autopsy. Wilson later finds House in Lupe's room. House explains that Lupe scratched herself with her bra hook and developed a staph infection.
House finds Foreman in his office and tells him to absolve himself for Lupe's death. He should only try to improve himself. Foreman is torn up that they blew such a simple diagnosis, but House consoles him that he'll do it again. This is a good thing. They are a special band of doctors practicing a special kind of medicine. They will miss on a few patients, but they will also save the ones any other doctor would think are hopeless causes.
That night, Foreman goes to his parents' hotel and tells his mother that he hurt somebody. She throws her arms around him and forgives him. She can see that he'd never hurt anybody on purpose. Foreman asks his mom if he knows who he is. She hugs him again and says that her little boy's name is Eric. Foreman is devastated.