Thirteen brings a woman, Spencer home with her and they have sex. Afterward, Thirteen goes to the bathroom and talks to Spencer in the other room. They're interrupted when Spencer falls out of bed, convulsing. Thirteen calls the EMTs who take Spencer to the hospital ER where Cameron admits her. Thirteen admits she doesn't know Spencer's name. Cameron brings the case to House, but he's busy playing a practical joke on Wilson. He goes into Wilson's office and finds him lying on the floor. House asks why Wilson was late and he claims he was meeting with someone for breakfast, but then eats a doughnut. Ecstasy doesn't account for the symptoms and House discovers that Thirteen knows about the case because she was with Spencer at 3 a.m.
In differential, House is interested in Thirteen's downward spiral and whether she was using drugs. Thirteen insists that Spencer has visited four other doctors who have found nothing, and she's just a hypochondriac who drinks too much. House orders Thirteen to take a bone marrow sample and goes along with her. Spencer cheerfully talks about her sexual affair with Thirteen.
House wants Lucas to investigate Wilson, noting he never eats a doughnut after a big breakfast. Lucas figures House is worried that something changed, but House tells him to check Wilson out.
Thirteen has discovered letters from Spencer to the hospital, and realizes she used her to get to House for treatment. Spencer admits she didn't expect Thirteen to be so aggressive. Thirteen prepares to discharge her but Spencer has a respiratory seizure. House now believes drugs are involved and Thirteen realizes that her place will need to be searched. She figures House will come up with a reason for her to stay there while he searches her apartment. She refuses to give him her keys so House takes Foreman. However, House has had Lucas make keys of all his team's apartments and lets himself in. House denies having Foreman investigated or having his key, then heads for the bedroom. Foreman notes that House knows very little about him. Foreman picks up a letter and pockets it while House finds no sex toys, indicating she doesn't have regular sex partners. He also finds an asthma inhaler and a spider. He shows the team the spider and notes the venom can cause respiratory problems. House also reaches into his pocket and removes the inhaler. Thirteen seems concerned until she sees what it is, and House figures she has something more incriminating to hide.
House orders Thirteen to check Spencer for spider bites. Thirteen says she wasn't interested in anything other than a one-night stand, but Spencer flirts with her and suggests there was potential. They start to kiss but Spencer can't feel Thirteen's hand on her hips. Thirteen reports the new symptom to House and the fact she has low potassium that indicates kidney problems. House proscribes surgery to remove calcification from the kidneys and confirm the diagnosis.
House and Lucas watch Wilson as he plays video games in his apartment. Lucas spots an attractive blonde going into the apartment and to Wilson's door. House doesn't believe it but Lucas notes that things change.
As Taub and Chase find the calcifications, Foreman talks to Thirteen and gives him the letter. It reveals she has less time then they thought and suggests she should be working out. Thirteen insists she's busy having fun and cramming as much into her life as possible, and dismisses Foreman's concerns. On the operating table, Spencer has breathing problems but they can't find anything in the lungs to indicate problems. They wonder if the airway collapsed and House orders a treadmill test.
Thirteen is administering an IV to herself when Cuddy comes in. Meanwhile, Foreman discovers from his family that House had Lucas investigate him. House admits he didn't find anything… because Foreman hasn't done anything interesting since he was 17.
Cuddy calls House in to inform him that she wants Thirteen to take a drug test or undergo suspension until she agrees to. House refuses to let Cuddy test his team and escorts Thirteen out… then tells her she's fired for failing at her duties. He then visits Wilson to get caught up. Wilson admits that he met someone new: an ex-prostitute. She wants to go to law school and he plans to help her with her tuition. House is skeptical and Wilson notes he's not in any position to be judgmental. House wishes him well and leaves.
Thirteen is going over Spencer's case trying to find something to impress House with when Foreman comes in. He still thinks she's acting stupid. She finds a dark spot on the x-rays that indicate a cyst. She goes to where Spencer has just collapsed on the treadmill when one of the cysts burst and revives her just in time.
House meets with his staff and orders the team to biopsy the cyst… and tells Thirteen she's still not going to be on the team. He then meets with House and tells Lucas about Wilson and the prostitute. House wants Lucas to find something on the prostitute to get her to back off. Taub interrupts them with the results of the lung biopsy. House then goes to see Thirteen as she packs to leave and points out that she has sex with women to control them, so she can get close to controlling herself. He then shows her Taub's report, which shows that Spencer has LAM and has no more than ten years to live. He suggests that Thirteen give Spencer the news, even though it has no bearing on getting her job back. She agrees and gives Spencer the news. They've removed the cysts, but they'll inevitably grow back. Thirteen describes what she'll go through and Spencer realizes she's dying as well. However, as Thirteen leaves she sees that Spencer is blaming due to anemia.
Thirteen tells the team the symptoms and asks for the chance to work on the case. Anemia eliminates LAM, but they have nothing to work on so House orders tests for everything. As he runs the tests, Foreman asks Chase if he's boring. Chase says that he is, and that he never takes chances or puts himself at risk. Meanwhile, Thirteen holds Spencer's hand, then gets into bed and they kiss.
House insists that Spencer needs a bone marrow transplant but Thirteen warns that she won't survive the graft rejection. House tells Thirteen tog et Spencer's consent, then returns to his office. Lucas is there and has Wilson's garbage, which contains drug syringes. House goes to Wilson and tosses him the garbage: he's figured it's Wilson's practical joke on him. However, House still wants to know where Wilson was the other morning. Wilson insists that it has nothing to do with House and they'll still be getting together regularly. House says fine, but Wilson realizes that House will follow him no matter what so he tells House where to find him that night.
Thirteen gets Spencer's consent and House points out she's in a spiral of destruction that won't end until she's dead. However, until then he can use her: he gives her her job back. She realizes that he wanted her to spend time with Spencer so she could connect with someone. As she talks, House notices her cracked lips. Then he asks if Spencer cried when she got the news she was going to die. Thirteen says no and House grabs an onion and goes to see Spencer. He cuts the onion but Spencer still doesn't cry. House explains that she has Sjoegren's, which caused infections that led to the anemia. The cracked lips were caused by infection but Thirteen only has the infection, not Sjoegren's. Spencer will be okay.
As Thirteen leaves for the night, Foreman congratulates her but she admits she feels alone even though Spencer is still there.
Wilson goes to a baby store to help Cuddy pick out a crib. House has followed him and Cuddy explains that she's adopting a baby. Wilson was testifying as a character witness the other morning and Cuddy didn't want anyone to know until she received approval. She asks if House is going to congratulate her and he abruptly leaves.
Thirteen has brought another girl home for sex.