Prosecutor Tommy is in court destroying the testimony of a man establishing an alibi for his friend, who is on trial for armed robbery. Tommy easily disproves the witness’ claim but then clutches at his chest and tells the judge that he’s asking for a continuance because he’s having a heart attack.
Later, Foreman brings the case to House, who is initially bored by what is either a simple heart attack or anxiety attack. However, Foreman assures him that he already tested for both of those and came up negative, and that he lied to Tommy to keep him from feeling further anxiety. Impressed, House takes the case to his team, and Adams suggests poison. He orders them to test and assumes that Tommy’s wife Olivia tried to kill him. He tells Chase to deal with Tommy and his wife while Adams goes to the home to do testing. When they point out that Taub and Park aren’t doing anything, House invites them to pick a partner and they both choose Park. Embarrassed, Adams says that it was a 50/50 choice and Chase quickly chooses Taub and leaves her with Park.
As they go to see Tommy, Chase and Taub run into Foreman in the elevator. They warn that he doesn’t have any excitement in his life so he’s decided to play games with House. Foreman denies it but Taub warns him as a man with personal issues that Foreman is taking some big risks.
Adams and Park drive to Tommy’s house and Adams tries to make small talk. Park accuses her of not liking her, but Adams figures that House is just trying to stir up conflict between them for his own amusement. Park doesn’t believe it and figures that House must have spotted some dislike toward her from her teammates.
Taub talks to Olivia, who insists that no one hates her husband, even the criminals that he’s put away. When he asks about the possibility of poison, Olivia explains that she cooks everything at home. Chase confirms that Tommy used to be a health inspector and became disgusted with processed foods after inspecting plants. When Chase asks the prosecutor if Olivia might want him dead, Tommy insists that he knows his wife and has dealt with hundreds of guilty criminals, and that she doesn’t have it in her.
Park and Adams test the house and come up empty, and Park worries that the neighbors will call the police because of the break-in. However, she’s soon intrigued by a discrepancy in the wall thickness and has Adams get her a kitchen magnet. Park uses it to pull out the shelving, revealing a bunker between the walls, and they call to tell House that Tommy has dozens of guns hidden in the house.
Back at the hospital, Park and Adams tell Tommy and Olivia about their discovery. Olivia admits that she had no idea there was a bunker, and Tommy explains that he secretly had it installed the last time they remodeled. They then go to see House, who is at the clinic calling off women’s names and then dismissing them. He figures that Tommy is an idiot for buying into the collapse of civilization, while Chase believes that the paranoia is a symptom. Park points out that Tommy might have legitimate concerns, and Adams scoffs at her. Adams insists that it was nothing when House follows up on her comment, but Park points out that she was rather harsh. The two women argue about the differential and House tells them to check all of their theories by testing for cocaine use and sleep apnea. He tells Park to work with Taub and then finally finds an attractive female patient to examine.
As Taub and Park prepare to test Tommy for sleep apnea, Park admits to her teammate that she thinks none of the others respect her. Taub tries to reassure her, and Foreman calls him out into the hall. He tells Taub that the nurses keep leaving him food and he figures that Taub is telling them that he’s looking for a girlfriend. Taub denies it and Foreman leaves, apparently satisfied. Park has been listening in and figures that Taub is lying, and he admits that he is but it’s for Foreman’s own good.
In the cafeteria, House and Wilson are discussing Tommy’s fears of a global collapse. House figures that he’s stupid, but Wilson points out that his friend is also paranoid and keeps a gun. When House denies it, Wilson claims to believe him but his friend doesn’t believe him and Wilson says that he’s not going to drop the matter.
Chase and Adams confirm that Tommy is negative for cocaine and argue back and forth. Adams insists that it doesn’t mean they hate each other. She tells Chase that Park is a good doctor, and Chase points out that Park is weird, Adams is weird, and even he’s weird. They discuss guns and Chase deduces that Adams keeps one for fun and because she can afford it, and says with a straight face that that he used rifles back in Australia to kill kangaroos.
Olivia offers to stay overnight with Tommy rather than go home to their children. She asks her husband why he wanted children if he thought the world was going to end, and Tommy explains that he was just being cautious and got the guns in case things turned out bad. As the couple talks, Park notices that Tommy has a bleeding lesion on his leg, and that he hasn’t even realized that it was there.
Back in differential, the team confirms that Tommy’s temperature went up over the night. The chest x-rays have turned up nothing and Park continues arguing that Tommy is reasonably concerned, not paranoid. House tries to provoke Adams into another argument with her teammate but Adams refuses to take the bait. As the rest of the team leave, Park confronts House and asks why he’s trying to manipulate her. House claims that it’s for his own amusement and wonders why she’s making a big deal out of it. When Park insists that she’s a good doctor, House tells her that her teammates may respect her skills but they don’t like her personally.
While Taub and Chase run the new tests on Tommy, he defends his actions to them, saying that he shouldn’t have lied to his wife but that he wanted to protect his family.
At the clinic, House checks on a stoner dude, Ethan, who claims that he has frostbite because his fingers are white. House tells him that he’s an idiot and that his fingers are coated with silver nitrate put on the company money to catch thieves. He tells Ethan to take a trip for 30 days because that’s how long it will take for the silver nitrate to wear off. He then gets a page and prepares to head out. Foreman is arguing with Nurse Regina and notices House leaving, but House says that he has an emergency page. When he goes home, he finds Wilson hanging in a net that he set earlier. Wilson admits that he was searching House’s apartment to find the gun he thinks that House has. House refuses to release him until Wilson admits that his friend is cleverer than he is.
At the gym, Foreman is working a heavy bag with an attractive woman, Anita, comes over and introduces herself. He assumes that Taub set him up again and tells her to stay out of the situation, but Anita explains that she just moved to Atlanta and doesn’t know anyone. Foreman is still skeptical and Anita tells him that she’ll be around if he wants to talk. Once she leaves, Foreman calls Taub, who says that Tommy is hallucinating and is going berserk.
When the team returns to the hospital, they argue differentials. Chase figures that Tommy is a schizophrenic, while Park believes their patient has a brain infection and should be treated with antibiotics. Adams votes for GAD auto-immunity, and warns that antibiotics will kill Tommy if administered. House goes with Adams’ differential and orders treatment. Park goes after him and accuses him of choosing Adams’ diagnosis just to mess with her. He denies it and continues to suggest that her teammates don’t like her.
House goes back to his apartment and finds a tripwire. He trips it and watches as a net shoots out. Wilson jumps out of a closet but realizes that House evaded his trap. He sheepishly leaves and House goes to his bathroom. However, the doorknob comes off in his hand and the other door is locked. Wilson is outside, smirking, and starts searching for the gun.
Foreman ends up with Anita, who takes him back to her apartment. However, a man calls out and she admits that her husband is back home, and then shoves Foreman out of the apartment.
Tommy’s fever continues, meaning he doesn’t have GAD. Park calls House, still trapped in his bathroom, and he tells them to give Tommy steroids. She warns that they could kill Tommy if they’re wrong and he has an infection, and House admits that because they screwed up all they can do is keep Tommy alive a little longer. Park says that they can still treat Tommy with the antibiotics and House goes with her differential, telling them to run DNA assays. When Adams complains, House tells her that Park convinced him and she should do what Park said. Once House hangs up, Wilson lets him out and admits that he couldn’t find a gun in the apartment.
At the hospital, Adams is disgusted that they’re wasting time looking for Park’s infection. Park starts arguing with her and Adams argues back. Meanwhile, Foreman talks to Taub privately and complains that he set him up with Anita, and that he’s happy with his relationship-free life. Taub doesn’t believe it, pointing out that Foreman came to the hospital at midnight just to chew him out. Foreman tells Taub to stop messing with him and leaves, and Taub tells Chase that Foreman dating a married woman isn’t a good idea, but it’s at least a start.
Tommy goes into anaphylactic shock and Chase tries to trach him without success. They realize the blockage is below the incision point and give him ephinephrine to get him breathing. The allergic reaction means Tommy doesn’t have GAD or an infection, but Park notes that it can’t be an allergic reaction because it would be gone after three days in the hospital. She suggests a combination of squamous cell carcinoma and paraneoplastic syndrome, accounting for the symptoms and undetectable by chest x-ray. House realizes that it’s the best they have and tells them to do a biopsy to confirm.
Back in his office, House gets a visit from Wilson. Wilson shows House the gun that he found in House’s apartment after he went back a second time after House figured he’d given up. House claims that it’s a magician’s prop gun used in a bullet-catching routine, and uses a pencil to demonstrate that the barrel is plugged. When Wilson doesn’t believe him, House puts one of what he claims are blanks in the gun and offers to let Wilson shoot him. When Wilson refuses, House offers to shoot him instead. Wilson finally accepts that he was wrong and walks out, and House drops the pencil the rest of the way down the unplugged barrel. As he slides the pencil in and out of the barrel, he gets an epiphany.
House goes to Tommy’s room and tells the team that he’s running a scope down the tracheal tube. He confirms that a pseudomembrane is blocking Tommy’s throat below the incision point, and explains that Tommy has diphtheria. Nobody detected it because they assumed Tommy had his inoculations. However, Tommy was so worried about the end of civilization that he forgot to get his shots. House has Park get antitoxin from the CDC, which should cure the diphtheria.
As they treat Tommy, Foreman comes in and congratulates Taub on another successful case. He explains that he was busy dealing with the hospital’s parking validation system. Olivia comes to see Tommy as he recovers and tells him that she’s moving out and taking the kids with her. When Tommy begs her to stay with him, Olivia says that he’s going with him, and that she refuses to live in fear in a house with guns.
That night, Foreman is working when Regina drops off some papers. She invites him to join her and some other staff members for drinks and nachos, but Foreman says that he doesn’t have time. The nurse tells him that he’s welcome if he changes his mind.
Park ends up riding the elevator down with Adams and Chase. She finally asks Chase to go out with her for drinks, because she’s decided what the heck. When he says that it’s not a good idea for co-workers to date, she points out that he married a co-worker. Chase concedes the point and says that he’ll think about it.
Foreman finally makes a call and tells someone that he’s changed his mind.
House takes the gun back to his apartment. He puts it in the closet with his father’s other Marine relic, a ceremonial sword.
Foreman goes to a bar and meets with Anita.