Cuddy tells House he will have to narrow down his forty applicants, so he immediately fires an entire row. Cooper pages House and offers him $50,000 to secretly cure her problem, which she describes as seeing sounds (synesthesia). She wants to keep it off the books so NASA does not 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. While talking to his applicants in his office, House thinks he sees Chase walking past the doorway. House orders Cooper into a hyperbaric chamber where Applicants 6, 18, and 24 attempt to flush out excess oxygen, but she collapses with a heart attack. They try to defibrillate, but it starts a fire in the oxygen chamber, setting off the sprinklers.
Later, they determine the attack was not caused by the treatment and House runs a differential. He then sends them to run tests and look for infectious substances in the cafeteria. House tells Wilson that he saw Chase, but Wilson says Chase is in the Mayo Clinic in Scottsdale, Arizona, and suggests House is feeling repressed guilt. House is not amused. Meanwhile, the oldest applicant, Henry, has one of the other applicants do a test that House assigned to him.
The applicants check in with House who orders thyroid tests. Cooper's temperature starts going up. The applicants inadvertently reveal they broke into her house, and she starts hearing vision again while concerned that they are going to out her. Cooper panics and has a psychotic attack, locking herself in the chapel. She eventually bursts out and they sedate her, but Cuddy notices and wants to know who Cooper is. House thinks he sees Cameron walk through the lobby.
Cuddy goes to the applicants for answers and they have to admit they do not 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 says she is in Arizona where she and Chase are engaged, and contends that House is going to choose people he cannot stand. House picks up on the idea of stress and suggests that they stress Cooper's liver. As he is leaving the room after having been fired, one of the applicants (Kal Penn) suggests they get her drunk. House likes his idea, and decides not to fire him. He decides to use some of the other applicants as a control group to see how quickly Cooper gets drunk.
After seeing his Brigham Young University class ring, House recruits a Mormon applicant, who initially objects on a religious basis, but then consents after arguing back and forth with House. 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 has ordered irrelevant tests, points out Foreman is working in New York City, and notices he has been drinking. He returns to the room to find they have taken her to the physical training room so they would have an excuse for giving her oxygen as part of a cardiac stress test. House determines she has lung cancer or tuberous sclerosis, and tries to order a biopsy. However, Cooper does not want a surgery that will leave a scar, so House tries to figure out a way to do it without causing scars. One of the applicants, Taub the plastic surgeon, proposes they suggest she undergo elective breast augmentation so they have a reason for the scars.
Cooper undergoes surgery and they biopsy the lungs, finding cysts. Chase shows up to suggest a diagnosis, Von Hippel-Lindau disease. After removing the cysts, House confronts Wilson who admits that Chase and Cameron are still working in the hospital (although Foreman is in New York). House visits Cooper and says he called NASA and told them what was up, as she posed a risk.
With Cooper diagnosed, House dismisses most of the applicants, and tells the rest to come back the next day. He confronts Henry and observes he has never been to medical school. The man admits he worked in the Columbia med school admissions office for 30 years and audited all the classes, but never got a diploma. House suggests that Henry could work as his assistant.
House goes to see Cameron in the E.R., and she reveals she's been working there for three weeks, and that she was the one who gave House's pager number to Cooper. House says he did not actually tell NASA, and lied about it to keep anyone else from telling them. Cameron is skeptical of his reason for doing so, suggesting instead that he was not willing to kill her dream. Cameron walks away.
House originally hired 40 doctors. Further details of these characters can be found on List of House characters#Fellowship applicants.