A mother and daughter are driving home from the skating rink and the mother is concerned that she fell, and that her friends weren't careful enough The girl, Hannah, is upset, and the mother is going to have the doctors check her and warn Hannah's friends off. They're hit by a truck and Hannah tries to get free to get her unconscious mother out. Hannah calls 911 and says she's fine… unaware that there is a piece of metal in her leg.
House comes in to find Foreman and spars with his current girlfriend, then sees him tending to Hannah. House quickly determines she is insensate to pain and orders tests suspecting something is wrong, then goes to talk to Cuddy. He quickly realizes that Cuddy has a blind date and teases her a bit. Hannah refuses to let them test and House goes to see her while poking away at Foreman about his relationship. House then confronts Hannah and they compare symptoms until House can trick her into letting him give her a sedative so they can run tests. Later Cameron checks Hannah's temperature and the girl passes out, overheating. They apply ice packs as she goes into shock.
House suggests a biopsy of the spinal nerve, risking Hannah's possible paralysis, but Foreman thinks it's just a fever. When his staff stands against it, House goes to Cuddy. Hannah's mother is in bad shape and so far they're keeping it from Hannah. To avoid testing her, Chase suggests they inflict more pain on Hannah to find a tender spot.
Cuddy meets with her blind date, Bobby, and they get along until House shows up to ask for the nerve biopsy. While House interrogates her date, Cuddy challenges the need for the tests and she quickly gives in.
Chase runs the pain tests on Hannah while she asks about her mother. Hannah inadvertently gets second degree burns and Chase tries to comfort her. Foreman then prepares to drill into her skull to inflict more pain. Foreman and Hannah chat about her mother and how she tries to get her mad, then Hannah starts to react. She runs off in panic.
Wilson confronts House about Hannah and how House is examining her out of curiosity. They're interrupted when Foreman comes in to warn she's prepared to jump off the second-floor balcony. They try to comfort her in her paranoia and then her legs go numb and she falls to the floor below.
They put the now-paralyzed Hannah back into bed and run more tests, but she's more concerned about her mother. They can't account for the paralysis but along with the paranoia indicates a neural condition. Cameron suspects the thyroid and House goes to check with a specialist… and goes to see Cuddy at her house, claiming he can't find anyone else. Her date is there with her and House eventually figures it out, and she points out he's suddenly interested in her and suspects he's jealous. House denies it and Cuddy leaves him at the door after telling her it isn't the thryroid. But Herrick overhears them talking and tells her that she's more interested in House than anything else, and he'd rather date that woman.
House goes back to run the nerve biopsy and he ends up going to Wilson, who points out that House is using Hannah's condition to find a cure for himself. He calls House on it, pointing out that House is biased and House stalks out and orders the biopsy the safest way they can.
Cameron and Foreman discuss their respective relationships, and the fact she married a dying man to avoid commitment. Cameron finds something interesting: Hannah's nerves are degenerating from something systemic that's affecting the nerves. Cameron interrupts to leave as Hannah's mother is out of surgery, and she's more concerned about reassuring Hannah then diagnosing her, to House's displeasure. Hannah's mother wakes up and is apologetic over causing the accident and hurting Hannah. Hannah's mother passes out and as she goes into surgery, Hannah starts feeling first her own tears and then a headache.
It's back to differential diagnostic and they conclude emotional pain caused the reaction and they were arguing about whose fault it was. House factors in guilt and suggests they give her a shot of B-12… but ER already did. House goes to see Wilson after ordering bone marrow tests for leukemia. House realizes she has B-12 deficiency and something else ate the injection. Hannah has another paranoid episode and takes her to the OR, interrupting the current surgery. They cut her stomach open without anesthesia and House removes… a 25' tapeworm.
Later Hannah's mother is brought in to see Hannah while Abby confronts Foreman who breaks up with her. She points out he's trying to maintain his personal space and his angry at him… and House. Cuddy is sleeping alone, while Wilson suggests that House ask Hannah for the nerve sample for his possible cure. House declines and they head out for breakfast. Chase and Cameron head out and she suggest they have sex, as Chase is the one she's least likely to fall in love with. Chase considers whether he should be offended… and then agrees.