The Trenton Toros, a minor-league hockey team, sends in their "enforcer", Bobby "The Hatchet" Hatcher. Bobby faces off against his opposite number, Szabo, and they agree to start a fight. Szabo goes down and Bobby retreats to the side, but starts coughing up blood and then collapses.
The team comes in to find House playing table hockey. He tells them that Bobby has hemoptysis and dismisses Taub's diagnosis of a punctured lung, pointing out that the ER already ruled it out. House has the team run tests and Adams and Taub go to get a stool sample from Bobby. Taub is a hockey fan and complains that fighting ruins the sports, but Bobby insists that what he does draws fire and protects his fellow players.
House finds Wilson sleeping in his office because the neighbor's baby is too loud. When House points out that Wilson has milk stains on his shirt, Wilson admits that he was taking care of the baby and House figures that he's having maternal urges. Wilson admits that he is and says that they're both missing out on something important. House then brings up the fact that eleven years ago Wilson slept with a woman, Beth Falconer. When they split up, Wilson staggered over drunk to House's apartment and passed out. What House has kept secret is that Beth called and says that they had unprotected sex. She now has an eleven-year-old son, Wilson's child. House didn't say anything because the next day, Wilson said that having a child would be the worst mistake of his life. Wilson doesn't believe it and House simply walks out.
Park and Chase run the MRI test, and Park complains that her mother Popo is at home alone because her husband is ill, and she has to take care of her. Chase suggests that she move out but Park believes it would be a sign of disrespect. They confirm that Bobby doesn't have sarcoid but they do realize that his spleen is swollen. In differential, Chase suggests a DVT and House tells them to do an ultrasound and blood test for leukemia. Taub takes the sample while Bobby gets a call from his agent saying that he's negotiating a deal to get Bobby into the majors. Meanwhile, Taub checks Bobby's chest and discovers that he's growing breasts.
That night, House goes out on his office balcony and sees Wilson on the adjoining balcony. Wilson admits that he called Beth and confirmed that he has a son, Duncan.
The next day, Park suggests that Bobby is an alcoholic but House is more interested in the fact she slept in her car. She admits that she had a fight with Popo, while Taub prefers to focus on the case. He suggests that Bobby is using steroids and House plays back the recording of the game, including a block that Bobby make. Taub says that it's a legal block but Adams agrees. House says that the league ruled it illegal and figures that Taub is biased and trying to hide it. He sends Taub and Adams to run antibody titers for lipto while Park and Chase check Bobby's locker.
As they check the lockers of Bobby and his teammates, Chase offers to put Park up at his apartment. She isn't comfortable with the idea of two single people living together, and then finds a prescription for mono. She figures that Bobby has Epstein-Barr and that would account for his liver damage. As they go, Park says that she'll take Chase up on her offer.
Wilson goes shopping for a present for Duncan and takes House alone. House figures that Beth hasn't said anything good about Wilson to her son and that Wilson isn't ready for a lifetime burden. Wilson insists that Duncan could be a good kid and that he wants to meet him.
When Chase comes home that night, he finds a little Korean woman knitting on his couch. Park comes in and explains that she let herself and her mother in. Popo is there because her father had to go to the clinic for his cyst and Park tells Chase not to worry about her.
When Taub checks on Bobby, he finds him curled in a fetal position on the floor, crying.
The next day, the team goes into differential and Park suggests liver damage causing hormonal imbalances. Adams figures that it's just a side effect and Bobby is doing okay. However, Taub believes that Bobby has CTE due to concussions. House figures that Taub is still biased and just wants a chance to dismiss Bobby's chosen career. Park realizes that House has figured out that she and Chase are living together and hastily insists that they're not having sex. Chase is less than thrilled when she says that they might have sex. House starts analyzing Chase's behavior and figures that he isn't doing it just to be nice. He suspects that chase is feeling guilty because he was the one who suggested that Park move out. When Taub suggests they do a MRI or CTE, House overrides him and says to do a psych eval and then discharge Bobby if the eval is positive.
Wilson takes Duncan to a diner and they try to talk. He gives the boy a present, a Gamedeck, but the boy says that he has one. As Duncan tries to put a good face on it and says he can use a spare, the waitress sees the toy and says that Wilson's a good father.
After running the psych eval, Taub tells Bobby that he's fine. He suggests that Bobby ask for a MRI but the hockey player refuses, saying that there's already plenty of evidence that he has head trauma.
Duncan talks to Wilson about what Beth has been saying about him all these years. He has to go but asks Wilson if he can hang out with him that night. Surprised and delighted, Wilson agrees.
Taub discovers that Chase has convinced Bobby to take a MRI on conditions of anonymity. He goes to the scanning booth and points out a density on the scan. Chase isn't convinced and Taub insists that he isn't imagining things. However, House speaks up from the MRI chamber, where he has set the whole thing up to show Taub that he's imagining things. Bobby strokes out and they get a page to check on him, leaving House stranded in the MRI chamber.
Later, House meets with Bobby, who has lost the use of his left eye. He confirms that Bobby hasn't had a stroke and is forced to admit that Taub was right that something more was wrong. However, House insists that Taub was wrong about the CTE. Bobby asks to talk to House alone and Taub and Chase wait outside. When House comes out, he tells Taub that Bobby threatened him if he didn't apologize to Taub for calling him incompetent. Chase suggests MPA, microscopic polyangiitis, but says that they have to run an ANCA panel to be sure. Taub disagrees, saying that the MPA could reach Bobby's lungs and they can't risk taking the time for plasmapheresis treatment. House sides with Taub and tells them to go ahead with the treatment.
In the cafeteria, House asks his friend if he's deliberately making himself miserable. Wilson insists that Duncan is a great kid, which only means that House figures the boy doesn't need Wilson as a father. Wilson tells his friend that he's making dinner but House says that no normal kid would want dinner and he's just going along with Wilson because he's just as gutless as his father. Wilson dismisses House's warnings as jealousy.
That night Wilson and Duncan are making pizza, and Duncan doesn't have much to say about himself. He finally asks if Wilson has prosciutto and goat cheese, and Wilson is happy to hear that his son has the same taste in food. After dinner, he takes Duncan home and the boy explains that he doesn't see much of his family. Wilson assures him that his family will be happy to hear that Wilson has a son. As he drops Duncan off, the boy hugs his father and calls him "Dad."
As Bobby undergoes plasmapheresis, Taub talks to him about hockey and wonders if he's happy. The doctor admits that he used to be a plastic surgeon but that it didn't make him happy. Bobby explains that he's always loved hockey, but as he grew older the high school coaches told him that he'd only get to play if he used his as an enforcer. As they talk, Bobby starts to panic when he realizes that his arms are paralyzed.
The next morning, the team goes into differential. Taub confirms that the ANCA panel showed no signs of MPA. Chase is clearly tired but explains that he was up late playing cribbage with Popo. House figures that Chase took the woman in because he feels guilty about screwing over other women, but Chase denies it. Taub focuses on the case and suggests that it's botulism but that it isn't Bobby's fault. House points out that Taub is now concerned about the patient since Bobby stood up to House for him, and notes that there's no indication of contaminated food. Taub suggest botox from a treatment to stop muscle spasms, but warns that they need to test because the botulism antitoxin could cause anaphylaxis. House points out that Taub is taking the opposite approach of what he did earlier, but Taub insists that it's a different situation. Unconvinced, House tells them to administer the antitoxin.
While Taub gives Bobby the antitoxin, Park comes in and wonders why Chase is being so nice to her. She wonders if Chase is sexually interested in her but Taub is highly skeptical. Bobby starts to regain the use of his arms and they figure that the treatment is working.
Wilson takes the elevator down with House and decides to thank him for not making him wait another eleven years to meet his son. House warns his friend that he's never had the kind of responsibility that a father has and that if he fails, he can't run away from Duncan like Wilson has run away from all of his other failed relationships. Wilson admits that's what he finds exciting about the whole thing.
As Taub and Bobby played table hockey, Taub admits that he's happier saving lives than doing plastic surgery. Bobby says that he feels safe in the penalty box and that he's decided that he won't do enforcing anymore, no matter what the cost. However, Bobby starts to choke as his lungs seize up.
Back at the conference room, Taub tells the others that there's no trace of botulism. House is out of ideas and Taub tries several increasingly desperate diagnoses. Chase suggests prion disease but Taub warns that due to Bobby's skull trauma, the required brain biopsy to test could kill him. House finally admits that Bobby wanted Taub off the case and didn't force House to apologize. He kept Taub on the case but wanted to show him how he would react differently. House then tells them to do the biopsy and leaves.
Duncan meets Wilson for lunch and tells him that Beth wants to move to Costa Rega to set up a bird refuge. She's always bought plane tickets, but Duncan doesn't want to go. He asks if Wilson will let him stay with him, begging him not to send him to the jungle. After a moment, Wilson says that it's okay if Beth is okay with it and Duncan hugs him.
Taub comes to House's office and asks his boss to take him off the case because he can't stay neutral. House agrees and wonders why he shouldn't take Taub entirely off his team. Taub admits that he has a problem with bullies, but House doesn't bother him because he thinks House is about ideas, not feelings. At least that's what he tells himself. He starts to go and House tells him that he screwed up and kept screwing up. House tells him that what he needs to do is trust nothing and question everything rather than just walk away, and play the whistle. When House says the last part, Taub gets an idea and House tells him that he can always trust ideas.
House and Taub go to the OR and stop Chase from doing the brain biopsy. Taub explains that Park was right and the mono gave Bobby Epstein-Barr. However, it also gave him Miller Fisher syndrome. The plasmapheresis helped him improve but they didn't realize why. When they realized he didn't have MPA and took him off of it, he got worse and then they gave him the antitoxins. House congratulates Taub on his diagnosis but points out that he screwed up the rest of the case.
House goes to see Wilson, who tells him that he's having Duncan move in with him. However, he's realized that House was right and he's not ready for that kind of responsibility. House tells him that he can make the whole thing go away and opens the door. "Duncan" is outside, and introduces himself as Wendel Wagner, a child actor that House hired to play the part. House assures his friend that he was just trying to realize what being a father was really like. Wilson orders them both out but then sits down, chuckling ruefully.
Taub checks on Bobby, who says that his agent has called and got him a $2.1 million deal to play in the majors. When Taub wonders if he'll be happy, Bobby says that half a dream is better than nothing and that hopefully his coaches will recognize that he can do more than enforce.
Chase and Park go down in elevator and he catches her staring at him. Park says that she isn't sleeping with him and Chase half-jokingly says that's a shame. She finally realizes that he's jealous of her and her family because he doesn't have one, and Chase admits that she's right. As they leave, Park says that she might sleep with him after all.
Later, Popo stays with Chase and plays cribbage. Park moves in with her relatives.
At home, Wilson invites House over to make pizza, and House explains that Beth played along with the whole scheme because she still hates Wilson.