A troubled teen collapses during her high-school Christmas program; Foreman and Thirteen learn more about each other as they work together on the Huntington's disease drug trial; House gives and receives holiday gifts, leading to team speculation; and Cuddy receives a gift as well.
A fitness guru known for her "natural" lifestyle collapses while shooting an infomercial. Meanwhile, Thirteen participates in a clinical drug trial for Huntington's disease led by Foreman; Kutner operates an online medical-advice clinic under House's name; and Cuddy moves into House's office while hers is being repaired, much to House's dismay.
A gun-wielding clinic patient (Zeljko Ivanek) takes House, Thirteen and several other patients hostage in Cuddy's waiting room and demands that House diagnose and treat him. The hostage taker also demands that House use other patients as guinea pigs for any medication he is going to receive. Thirteen volunteers for the treatment.
While Foreman takes on a pediatric case on his own, the rest of the team deals with a 16-year-old factory manager and emancipated minor who collapses at work. When Foreman's patient takes a turn for the worse, he's forced to question whether he can deal with the situation on his own, or if he needs House's help.
The team must treat an agoraphobic who refuses to leave his house, and have to work around Cuddy, who is less than thrilled at having hospital equipment relocated. Meanwhile, House is plagued by an itch, and Cameron and Chase have relationship issues.
An ailing man suffers from blackouts and sleepwalks, leading the team to wonder if his sleepwalking is a symptom, or how the man is becoming exposed to something else. When the man's daughter grows ill as well, the team must provide a diagnosis before both die. Meanwhile, Cuddy adopts a newborn but when the birth mother displays a rash, she has to make a decision between putting the mother or daughter at risk.
Thirteen brings her one-night stand to the hospital after the woman has a seizure. However, the woman admits she slept with Thirteen just so she could get to House and have him diagnose her condition. Meanwhile, House continues to pay Lucas to spy on Wilson.
While en route to his father's funeral, House must help the team with a differential diagnosis on a young Chinese girl who has collapsed under mysterious circumstances.
A painter's undiagnosed illness affects his work, and House and his team must look at the man's paintings to determine what's wrong with him.
An organ donor's organs are responsible for the deaths of several patients, and the team work to save the last two recipients. Meanwhile, House hires a private detective to keep tabs on his team as well as Wilson.