A tuba instructor starts coughing up blood in the middle of a lesson and expires.
Thirteen interrupts a college class to confirm the math instructor, Apple, had a corneal transplant five years ago, then informs her that four other people who received a transplant from the same donor died.
Apple is taken to the hospital where they determine four of the victims are dead and one more, an elderly man named Frank, is on the verge of death.
The team is unable to determine a common denominator and House is more concerned about Wilson's absence.
Foreman arrives to inform House that Apple's eye is failing and they have to remove it.
The coffee machine repairman interrupts to berate Taub and Thirteen for being idiots.
House returns to the hospital where Kutner and Foreman inform him the colonoscopy proved clean.
House still believes in cancer and Kutner suggests they use a high-pressure water jet to apply pressure to Frank's colon.
He goes to her room and signals an emergency when he cannot find the medical records on Apple's bed.
House gets a page and heads to the hospital where Apple is vomiting from the chemo but her system is stabilizing.
Wilson refuses to participate and warns he will not answer the door the next time House knocks.
Chase suddenly realizes that House had somehow had the IV switched, triggering the operation by deception.
Chase wants to abort the operation, but House observes that they've already completed the most dangerous procedure, so they might as well continue.
Lucas comes into the observation gallery and is alarmed that the patient whose IV he had switched is undergoing such a serious operation.
He takes off the bandages over her eyes and Apple sees the world with normal vision.