The initial diagnosis is hyper-anxiety, but the team finds an arsenal at the patient's home and start to believe that his extreme paranoia is a physical symptom.
Wilson becomes convinced that House is lying about not having a gun, which leads to an epic battle of wits between the two men.
Park tries to be more social with her workmates, while Taub and Chase wonder why Foreman hasn't had a romantic relationship in a while.
In the middle of devastating a witness on cross-examination, a district attorney goes to the judge to ask for a recess because he thinks he is having a heart attack.
House thinks it's an anxiety attack, but Foreman has already ruled it out by lying to the patient to get him to relax.
Chase and Taub run into Foreman on the elevator and compliment him for lying to the patient to rule out anxiety.
Adams is telling her how wonderful her new car is, but Park thinks she's avoiding talking about why she doesn't want to work with her.
Adams assures Park that House's belief that no-one wants to work with her is simply his way of getting under everyone's skin.
Chase asks him if he got any strange packages or letters, but the patient denies it and notes his three kids are healthy and it's unlikely they would not have been exposed to something that made him sick.
Park sees a spot behind the books, applies the magnet, and swings back the bookcase.
When Park and Adams go to confront the patient about the discovery, he explains that he built it in secret to keep the city from finding out.
Park and Adams go to report to House, who has already figured out what the patient told them - that he was afraid the government was going to collapse.
He replies he doesn't think the patient has a mental illness and tells Park not to let House get to her.
House says he doesn't need a gun, the only thing worth stealing would require a crane to remove it.
House is very attached to his possessions and likes dangerous things even making fireworks.
They start talking about the “feud” and Adams wants to know why Chase didn't pick Park that morning.
Foreman and Nurse Regina are arguing about why the paperwork hasn't been entered in the computer when House leaves the clinic early because he got an emergency page.
When he goes to answer it, a beautiful young woman, Anita, introduces herself and asks him how bad his day was to take it out on the punching bag, but Foreman thinks Taub sent her and threatens to treat him like the punching bag.
Adams and Park argue about whether it's new or old paranoia when Chase interrupts to suggest it may just be a mental illness because all the tests are negative.
The trap springs harmlessly and Wilson delightedly jumps out of the closet only to have his spirits fall when he sees House standing untrapped.
House returns triumphantly to his apartment, only to lock himself in the bathroom when the doorknob comes off in his hand.
House finally gives in, but tells them ordinary antibiotics would be useless - they need to identify the infection.
Adams reminds him that he just ordered more steroids, but House tells her he changed his mind and to follow Park's instructions.
Wilson finishes searching House's apartment and admits there's no gun, although he found his own sunglasses, tennis racket and money clip.
Taub tells Foreman he needs a life so he won't come back to the hospital at midnight just to yell at him.
They manage to get the patient breathing again, but they realize the anaphylaxis and edema rules out both infection and GAD.
House turns back to toxins, but there was no-one with the opportunity to poison the patient on all occasions.
When Wilson turns around, House lets the pencil drop all the way into the barrel, showing us the gun is real.
House asks for a bronchial scope and warns the patient he won't be able to breathe, but he has to look down his windpipe through the tracheotomy hole.
Music playing at the end of the episode is the song "Waking Life" by Schuyler Fisk.