This is the 150th episode of the series and marks the return of Thirteen, whose whereabouts have been unknown to House's team for the last year.
When she replies that she was in jail for "excessive prescribing", House states that this was only her plea bargain and not the truth.
Meanwhile, back at the hospital, Masters presents a case to her teammates: a 36-year-old teacher coughing up blood.
Foreman and Taub search the patient's house, and find out that he is a hoarder and come up with aspergillosis for a diagnosis.
House figures out that Thirteen had euthanized her brother, who like her mother, suffered from Huntington's disease.
Thirteen admits this and explains that her brother had asked her to end his life in one of his increasingly short periods of lucidity.
She tells him that she knows that she will one day reach similar state and that no one will be able to help her in the same way, a plaintive declaration that clearly troubles the silent and pensive House.
However, Thirteen takes his silence as a lack of emotional response, and tells him, "it's no wonder Cuddy broke up with you".
Masters finds baby clothes among the hoarded stuff at the house and confronts the couple about this, bringing a new symptom to the table - infertility.
House, driving back from the competition with Thirteen, asks the team to confirm the validity of the symptom by checking both husband and wife, ignoring Thirteen's attempt to quietly suggest another option without participating in the discussion.
The team is excited to hear from Thirteen, but House asks them to save their chatter with her for when she returns the next week.