Chase wakes up with a woman in bed with him. She points out that he's bleeding, and asks if they need to get to a doctor, and Chase assures her that he's a doctor. House calls him and Chase gets out of bed and up onto his crutches. The woman, Cindy, asks what caused his accident and Chase tells her that he was stabbed by a patient. He checks the wound and then gets a new text message from House saying that he's just outside. Chase answers the door and House describes the case of a 45-year-old truck driver with seizures. When Chase points out that it's not a good time, House says that he's paged him repeatedly over the last three weeks and he's still waiting for Chase to accept his apology. When he asks if Chase is coming back, Chase says that he doesn't know and tells House to fire him if he has a problem with that.
Later, Chase is undergoing therapy at the hospital and Foreman comes by to see him. He asks if he's coming back to work, even if it isn't for House, and warns Chase that he'll lose his mind if he doesn't put himself to work. Chase goes to do his 20 hours of clinic duties and finds a nun, Sister Moira, there. She complains about shoulder pain. Sister Joan is there with Moira and says that Moira didn't do anything to cause shoulder pain. Chase suggests that it might be a symptom of breast cancer and asks Sister Joan to leave so he can do an exam. Once she leaves, Chase says that he wanted her out of the room so he could ask Moira if she is suffering from stress brought on by the fact that she's preparing to take her vows. He explains that he was a seminarian and Moira admits that she has had second thoughts. He performs the breast exam and finds a mass, and admits her to test.
Chase has Wilson run the tests, which show that the mass is a fat deposit. The stress test is also negative. House comes in with the rest of the team, admitting that he had Park follow Chase. When House points out that the patient is a nun, Chase says that he doesn't want his help and says that maybe he's realized what House was like after all these years. As he tries to leave, House suggests that Moira has a fungal infection from the wheat in the unprocessed bread. Chase leaves without a word and Park runs after him to apologize. She suggests that they go out for a meal, but insists that it isn't a date. Park suggests that he just needed someone to talk to, and Chase says that knowing she's there is enough.
As he treats Moira, she asks him if he's ever surfed in Australia. She explains that she grew up on Maui, and Chase asks Moira wants to be a nun. Moira explains that she worked as a nanny, moved around a lot, and had a lot of failed relationships. Finally she heard the call from God, but admits that there wasn't a dramatic moment. She wonders if Chase had a dramatic moment, and he explains that he was raised in a Catholic church. Moira starts vomiting and Chase realizes that it's not a fungal infection.
House is busy filling a soda balloon in the lobby when Chase comes over. He starts to explain that Taub has started a prank war, but Chase asks for his help and tells House that it's not a fungal infection. House wonders what he plans to do if he isn't on the team, and points out that Chase has come back to the same building he has worked there for years. He wants Chase to admit that he's a confused mess, but Chase figures that he'll take the case just to find out why Chase is interested. House suggests ascending cholangitis and then drops the soda balloon on Taub as he passes, and just misses him. Chase disagrees with the differential but House notes that the signs could take a while to develop. When Chase goes back to Moira's room, he discovers that her feet are numb and realizes that he'll have to consult with House.
Chase goes to the conference room where the team is going over another case and admits that he needs help. House responds by firing a paint gun at Taub, testing the fact that he's learning martial arts to cope with dangerous patients. Taub notes that he's already fended off six of House's attacks, but House says that no can teach people to expect unexpected things. He then suggests that Moira has a blood clot while he attacks Taub, who disarms him. Adams suggests a vasospasm and House suggest a calcium channel blocker to treat.
Adams catches up to Chase as he leaves and asks if he's okay. He reminds her that he almost got her killed, and Adams pointed out that he saved her life. Adams wonders how he can't be traumatized and Chase tells her that all he can do is make better choices in the future. She says that she's seeing a trauma counselor and suggests that he do so as well, but he says that knowing she's there is enough.
Chase administers the blockers and notices that Moira has borrowed an iPod from one of the nurses. He points out that he's never seen her use rosary beads and quizzes her on her knowledge of the Bible. Moira says that he can't argue away her faith even though it isn't that strong, and admits that she hasn't felt the calling yet. Chase is surprised since no one takes their vows without taking an epiphany, but Moira says that she needs the silence and hopes the epiphany will come later. He doesn't believe it but Moira stands by her beliefs even though her decisions will separate her from other human beings. She knows that Chase would miss that because she's talked to the nurses, and Chase says that there's nothing wrong with fun. He wonders if someone broke her heart but Moira says that she's just looking for something more. Chase says that he is as well and then leaves for the clinic to do his hours.
At the clinic, Chase finds Taub waiting for him. Taub explains that he's hiding out from House, and Chase asks if the self-defense s are helping. In response, Taub says that House's attacks on him are what are helping him, and he thinks Chase should come back because House will help him as well. Chase turns and leaves.
That night, Chase checks on Moira, who is recovering from her symptoms. While Sister Joan goes to get the car, Moira explains that six years ago she was a nanny in Honolulu for a two-year-old boy. He died while under her care, hit by a car, and Moira blames herself. Chase tells her that she shouldn't run from what could be a good life, but Moira insists that she's running to God. She asks if Chase wants to remake his life, but he refuses to hide himself away and wishes her well. When Moira admits that it will be hard not touching anyone, Chase takes her hand briefly and then watches as she leaves.
As Chase leaves, House is waiting for him and figures that he's hitting on a nun. Chase denies it but House suggests that he's terrified of intimacy and grasping for an emotional life raft. Unimpressed, Chase says that he has a date and goes to meet her. She's an aspiring actress but Chase is clearly bored. He finally admits that he is bored, breaks off the date, and goes home. He finds Moira sitting outside of his apartment door. She admits that she was running away and takes his hand. They kiss and then go into his apartment.
The next morning, Moira puts on a shirt and then cuddles with Chase. He wonders if they're both damned, and Moira admits that her plans changed when she met Chase. However, she figures that he isn't the relationship type and says that he's fine. Chase asks what is next for her and she says that she plans to find a place to live and get her job back. She blanks out for a moment and Chase notices a swelling on her neck. She then vomits up blood and Chase drives her to the hospital. En route he explains that the artery taking blood to her brain is breaking apart. The artery has clotted up, meaning it's bad. He gets her into the ER and orders off Park when she tries to help, and then gets Moira into the OR as she begins to lose brain function.
As Chase organizes the team to operate, House quickly realizes that Chase slept with Moira. The clot breaks and Moira starts coughing up blood, and Chase prepares to operate. The team disagrees, warning that his judgment is compromised. They turn to House, who tells Chase to do the surgery. Adams accuses House of trying to score points with Chase, but House says that Chase is the better surgeon. However, Adams and Taub continue to disagree as Chase tries to stop her from stroking out. He ignores them and makes the incision to remove the occlusion. With time running out, Chase uses ultrasound to make sure that the flow is good and then wakes her up without removing the anesthesia. Moira wakes up and Chase confirms that she has restored mental function.
Afterward, Park apologizes to Chase for earlier and he figures that she's scared. He asks her what she's scared of and she admits that she's afraid of everything. Chase tells her that she'll get over it, but Park says that she left the room and it was pure luck that she wasn't hurt. He irritably tells her that he doesn't have time to teach her how to be a doctor, and then goes over to tell House that there were nodules. The tests are negative for lupus, and House is busy watching Taub. He's assigned him fraudulent lab work to make him paranoid, interrogating an innocent janitor, and House is now ready to shoot him with a super-soaker. As they wait for Taub to approach, House suggests that the nodules are plaque, meaning that it could be syphilis. House then spins around the corner and fires, only to discover that Taub has rigged the super-soaker to shoot in House's face.
Chase talks to Moira, who says that she hasn't had sex for six years. He says that it's tertiary syphilis, which means she had it for six years and it isn't contagious. Moira asks if it could cause hallucinations, explaining that during the operation she saw the boy who died. He took her hand and forgave her, and Chase says that it should help her move on. Foreman and Adams call Chase out, since Adams has told Foreman that Chase slept with him. When Foreman orders Chase off the case, Chase insists that his judgment is fine and that he saved the patient. Foreman refuses to yield and leaves, and Adams apologizes. Chase reminds her that he took the scalpel for her, and Adams says that he needs help. When Chase insists that all he needs to do is get away from House, Adams points out that he's turning into House. They get a page and go to see Moira, who is complaining of stomach pain. Adams confirms that it's her liver.
Back in differential, Chase tries to diagnose and suggests thrombus. House disagrees and Park suggests that it's disseminated t-cell lymphoma. Chase thinks they need to biopsy to confirm cancer but House says that he's grasping at straws and warns that there's nothing they can cure. When Moira gets the news, she realizes that if she has cancer then the best they can do is use chemo to extend her life a few months. Chase assures her that he'll be there for her. Moira asks why he left the seminary, and Chase explains that he had an affair with the wife of the groundskeeper at the seminary. She asks why he didn't tell her before, and Chase admits that it made him sound shallow. Moira figures that he was struggling to find a reason to belong there and the affair was a symptom, and Chase says that he was never able to believe. As she tries to tell him it's too late, Moira has trouble talking because her jaw muscles are "heavy." As Chase leaves to find House, he sees the janitor that House has paid go after Taub. Chase tells House that Moira has jaw claudication. House agrees and orders steroid treatment, and then asks Chase what he will do next.
Once Moira recovers, Chase tells her that he'll take her to Mexico to surf. However, she tells him that she felt the calling in the operation room and she's going back. Chase says that it isn't real and is only oxygen deprivation, and admits that he loves her.
Later, Chase is reading up on near-death experiences and House discovers what he's doing. House figures that he's preparing a presentation to keep Moira from going back and says that Chase is an idiot. Chase insists that Moira is throwing away her life but House says that she's found an illusion that satisfies her and Chase is going to take it away. He figures that Moira will eventually resent Chase for taking away her illusion, but Chase figures that House just resents him reassessing his life. As Chase goes, House says that people reassess their lives when they make mistakes, but Chase just got stabbed.
When Chase goes to Moira's room, he sees her praying over her rosary beads. He throws away the presentation and goes in. After a moment they hug. Chase then goes to see Park, who is preparing to do a jugular test and reading a book. He tells her not to look at the books and walks her through the procedure.
Later, Chase goes to see Moira as she leaves. He tells her that he's happy he knew her and Moira says that she's happy as well. Chase turns and goes, but Moira calls him back and takes his hand again, smiling. As she goes back, Chase hobbles away.
A few days later, Chase is back at work and goes into the conference room to rejoin the team. House looks at him for a moment and Chase nods to him.