Cuddy and Foreman speed-walk down the hall after seeing that Melinda didn't take any of her street clothes with her when she escaped, meaning that she's still in the hospital somewhere. Or she's following her usual pattern of incredible stupidity and has gone out into the cold April air wearing only a thin hospital robe so that she can get pneumonia and have to get both lungs transplanted. Foreman uses his psychic link with Melinda to figure out that she's on the roof, and takes to the staircase to retrieve her. There he finds Melinda, perched on the top stairs, afraid to actually go on the roof. "I hate her," Melinda says. Did she run into Stacy on the roof? Or Season 1 Cameron? Foreman takes a seat next to her instead of immediately taking her sick ass back to her hospital bed, and starts to tell the same story about his childhood that he tried to tell Melinda's mother. The apple doesn't fall far from the tree of not caring about other people's life stories, though, as Melinda interrupts him to say that her mother was this overprotective before her transplant and that, if anything, the heart transplant just gave her mother the ammo she needed to keep Melinda indoors. Foreman gently suggests that there's a time and a place to be a typical whiny rebellious teenage girl who resents her mother, and that recovering from heart failure isn't exactly it. Melinda says she was too scared to go out on the roof when she had the chance, meaning that she's internalized everything her mother has said to her about the dangers of the outdoors. Foreman takes her hands and leads her back down the stairs to her room as he wonders if Chase will be willing to listen to his childhood-illness story. Cameron isn't an option, of course, since she surely has a sob story about a childhood illness that either she or her Poor Dead Husband suffered from that will trump Foreman's. Melinda walks down the stairs ahead of Foreman, allowing him to notice that she's dragging her left foot behind her.
We cut to Melinda on an examining table, the parents she hates at her side. Foreman says that Melinda has "stoppage gait," which is "not necessarily" serious. So obviously, she's doomed. Indeed, the muscles above Melinda's knee start spasming, which Foreman says means that Melinda's stoppage gait is actually ascending paralysis of unknown origin.
After the commercial, Melinda's paralysis is spreading quickly up her leg. House studies the Whiteboard and mutters that if they couldn't link the heart failure and the anaphylaxis to each other, then they certainly won't be able to link heart failure, anaphylaxis, and paralysis. Cameron offers up a diagnosis of tick paralysis that everyone laughs at, since they didn't find a tick anywhere on Melinda's body and they've already explained the anaphylaxis away with the penicillin sperm. Foreman wants to pretend that the heart failure and anaphylaxis didn't happen and concentrate solely on the paralysis, since that will kill her first -- a tactic that worked so well when he tried to do it for her heart failure before. Everyone offers up a few suggestions, including old favorite Guillain-Barré, and House orders up a bunch of tests to check for all of them. He even admits that Foreman is right that they need to figure out what's causing the paralysis, which shocks the Cottages into speechless amazed stares, for which House promptly makes fun of them all.