A pilot, Captain Greta Cooper, is flying in on an Air Force mission when she sees lightning and the landscape suddenly turns into strange colors on her. It turns out she's in a simulator and complains to the designer after crashing it.
House is busy tormenting his forty applicants when Cuddy tells him he'll have to narrow it down. House fires one row and storms out, and Cooper manages to page him and offers him $50,000 to cure her problem, which she describes as seeing sounds. She wants to keep it off the books so NASA doesn't find out and disqualify her as an astronaut applicant. House is intrigued and agrees, and has her present her symptoms to his applicants. He then splits them up to run various tests… and wash his car. Amber convinces all of the candidates (execpt for one) not to waste their time washing the car, then steals the keys and takes it to a car wash. (The next time he sees her, House asks her to return the keys.)
House meets with some of them but thinks he sees Chase walking past outside.
Three of the candidates go to Cooper's apartment. While two of them are trying to break in through the window, the third ("the old guy") gets in by telling the superintendant that he is worried about his "niece." They find a blocked flue in a gas heater, and suspect that she is suffering from carbon monoxide poisoning. House has Cooper put into a hyperbaric oxygen chamber to flush out the carbon monoxide. While in the hyperbaric chamber, Cooper collapses with a heart attack and goes into ventricular fibrillation. The defibrillator starts a fire in the oxygen chamber, setting off the sprinklers.
Later, they determine the attack wasn't caused by the treatment and House runs a differential. He then sends them to run tests and look for infectious substances in the cafeteria, and chats with Wilson, saying he saw Chase. Wilson confirms Chase is in the Mayo Clinic in Arizona, and suggests House is feeling repressed guilt. House isn't amused. Meanwhile, the oldest applicant, Henry, has one of the others do the tests.
The applicants check in with House who orders thyroid tests. One of them notices that Cooper is restricting them, and her temperature starts going up. They inadvertently reveal they broke into her house, and she starts hearing vision again while concerned that they're going to out her. Cooper panics and has a psychotic attack, locking herself in the chapel. They call House and he tries to get her out, but he's distracted by apparently seeing Cameron come in. Cooper bursts out and they give her a sedative, and Cuddy wants to know who Cooper is.
Cuddy goes to the applicants for answers and they have to admit they don't know much… until one of the applicants squeals. Cuddy insists that House document everything. After figuring out who squealed, House goes to the chalkboard and tries to figure out how to test Cooper without having to document them for Cuddy. House gives them an hour then goes to Wilson to find out why Cameron is there. Wilson confirms she's in Arizona where her and Chase are engaged, and contends House is going to choose people he can't stand. House picks up on the idea of stress and suggests that they stress Cooper's liver. Finally, the last guy House tried to fire suggests they get her drunk… and use some of the other applicants as a control group, including House himself.
House recruits a Mormon applicant, who objects on a religious basis, and they argue back and forth. House takes a couple of drinks… and sees Foreman outside. House goes outside, while Cooper has breathing problems but refuses treatment. Cuddy interrupts House's pursuit and wants to know why he's ordered irrelevant tests, points out Foreman is working in New York, and notices he's been drinking. He returns to the room to find they've taken her to the physical training room so they could give her oxygen off the records as part of a cardio-stress test. House determines she has lung cancer or tuberous sclerosis, and tries to order a biopsy. However, Cooper's refuses and House tries to figure out a way to do it without scars. One of the applicants, Taub the plastic surgeon, proposes they suggest she undergo elective plastic surgery on her breasts so they have a reason for the scars.
They convince Cooper to undergo the surgery while Cuddy demands answers. However, House points out she'll let him do it and is just going through the motions, and she trusts him to do what's in Cooper's best interests. She simply walks out.
Cooper undergoes surgery and they biopsy the lungs, finding cysts. Chase shows up to suggest a diagnosis, Von Hippel-Lindau Syndrome. After removing the cysts, House confronts Wilson who admits he called Chase in, Foreman is still in New York, but Cameron has been working in E.R. for the last three weeks. House visits Cooper and says he called NASA and told them what was up, as she posed a risk.
That night, House confronts the applicants and starts dismissing some of them, and telling the others to come back the next day. He confronts Henry and observes he's never been to med school. The man admits he worked at Columbia as an administrative assistant and audited all the s, but never got a diploma. House offers him a position as assistant for now.
House then goes down to the E.R. where Cameron is, and reveals she's been working there for three weeks and gave Cooper House's pager number. House admits he lied and didn't tell NASA, supposedly to keep her from crying and to make sure she stays safe. Cameron is skeptical and notes that he wasn't willing to kill her dream. House just walks away.