You Don't Want to Know

"You Don't Want To Know" is the eighth episode of the fourth season of the American TV drama House and the seventy-eighth episode overall. It aired on 20 November 2007. Notably, in this episode the differential diagnosis is confirmed as lupus despite the fact that 'It's not lupus - it's never lupus' is a phrase often used to the point of catchphrase by the eponymous Dr. Gregory House.

Kutner and Cole are in the audience of a magic show in a night club in Atlantic City. Flynn, the magician on stage (played by Steve Valentine), is replicating Harry Houdini's famous Chinese Water Torture Cell act, calling Cole up to the stage. Wrapped in chains, Flynn is dropped in the tank and loses consciousness as soon as he enters the water.

Kutner suggests taking the case of the magician. He wants to run tests to find out why Flynn's heart stopped in the water, though House is sure the magician has lost consciousness because he screwed up the trick and drowned. He permits Kutner to test the patient, but he says that he will fire Kutner if the patient's problems were a result of screwing up the trick.

Flynn says that he is a great magician, and did not fail to carry out the trick. To demonstrate, Flynn asks Thirteen to pick a card from a deck, and then asks Kutner for his wallet. The wallet bursts into flames, and when it is extinguished, the card she picked is in it.

Kutner tells Foreman that the tests show there was no cause for the heart failure. Foreman suggests running a lung MRI, but Flynn starts bleeding internally as soon as they start the MRI. He has had three units of AB positive blood transfusions, so Thirteen wonders if he has had an intestinal infarct. House realizes what caused the problems with the MRI. While Flynn is being operated on, House steps in, sticks his hand in Flynn's gut, and pulls out a key. Flynn had swallowed the key for the magic trick, then the MRI's magnet had ripped it through his intestines.

House confronts Flynn, but Flynn still insists that he is a great magician. To demonstrate, Flynn has House pick a card. Then he throws the deck of cards at the wall. A card sticks to the window, but is not the card House picked. House removes the card and is about to scold the magician when he sees his card stuck on the other side of the glass wall. House cannot figure out how he did the trick. Suddenly, the magician starts to bleed profusely out of his nose. House realizes something is still wrong, and Flynn's cardiac arrest is actually a symptom of something more serious. House gathers the Fellows in his office. Amber suggests that Flynn has Polyarteritis nodosa. Taub throws out the possibility that the nose bleed was caused by cocaine. House tells Taub and Kutner to go to the patient's home. He orders Amber and Cole to do a biopsy of Flynn's heart.