At the Princeton-Plainsboro Teaching Hospital clinic, House tells Wilson of the conditions for bringing Cameron back: a dinner date, which bewilders and excites Wilson, knowing Cameron is affectionate for her boss. As House leaves, he bumps into Harvey Park in the waiting room, whom he insults when he believes that Harvey spilled a sample of urine onto his clothes. Prodded by Wilson (who informs House that the spilled liquid was really apple juice) House reluctantly apologizes, until he discovers Harvey's right pupil is blown, resulting from a stroke. Meanwhile, Cameron is back and Foreman and Chase greet her return. House, with a new case in hand, has the team analyze Harvey's condition. On the CT scan, Foreman notes ischemia, death of brain tissue, and suggests an MRI to find the underlying cause, but Cameron states it will kill him, as a metal plate in Harvey's jawbone prevents it. House has the team do tests to rule out vasculitis, peripheral neuropathy, drugs, and cardiac emboli, while reminding Cameron to keep the conditions of her re-employment as discreet as possible.
Foreman discusses the case with Harvey while his friend Annette Raines is by his side, although to Chase it seems as if she is the one who knows more of his condition than it appears. At the clinic, an elderly patient named Ramona complains to House of vaginal pain, and states her husband, Myron, has been taking Viagra recently. She complains all they do now is have sex, and suggests House give Myron a prescription for something weaker; he tells her she would do better to tell him her real feelings. The team regroups, diagnosing a clot that led to the stroke, but where it originated is unknown. Chase suggests a trauma-induced aneurysm, but is brushed off, as no medical evidence supports this theory. Before they can start Harvey on blood thinners and antibiotics, they find Annette strangling him. They restrain her and Chase confirms his suspicions: Annette is a dominatrix, and Harvey is into S&M.
The team gives Harvey blood thinners and antibiotics and with his theory now supported, Chase suggests vascular surgery to find the aneurysm and repair it, but only if Harvey strokes out again. Meanwhile, Myron personally comes to House for a refill of Viagra, but claims that it is he who can't take much more sex. Annoyed, House gives Myron some placebos and sends him away. Harvey continues developing mini-strokes and won't consent to surgery. The team brings Annette, who is barred from re-entering the hospital, to convince him but to no avail, so they search for his parents. Chase and Cameron head to Harvey's apartment, finding various S&M gear and clothing and an address book. Chase also notices a slew of mint Tic Tacs and takes some for himself before he leaves. The team notifies the parents, but they are unwilling to help their son, due to his lifestyle. House argues even though they are humiliated by his sex life, it would be more humiliating for them to have him die because they would not sign a consent form. They relent and surgery is scheduled.
That night, House and Cameron finally go on their dinner date, she intending to discover how he feels for her. House says that he believes she is only attracted to men who are damaged, and it is this impulse, rather than love, that drives her; this being the reason that Cameron married her terminally ill husband. The next day the surgeon informs the team that there is no sign of the aneurysm. As House sends them to do more tests Myron and Ramona come seeking him again. The elderly couple bicker that one wants more sex and another wants less, until House sees both of them wearing different wedding rings, and deduces the two are married, but not to one another. They are, in fact, involved in an affair, with the problem lying not in the Viagra, but in themselves. The two confirm it, and when Myron reaches for his breath spray to make up with Ramona, Harvey's condition finally hits House.
The Tic Tacs Chase took from Harvey's apartment were a sign that the patient was trying to cover bad breath. House forces Chase to smell the inside of Harvey's mouth, who states it smells of vomit, pointing to fulminating osteomyelitis, an infection of the jaw. Infected tissue from the jaw breaks off, blocking blood flow to the brain, leading to Harvey's stroke; the metal plate hid it from their scans. House schedules surgery to remove the infected jawbone and Harvey recovers. Before he is discharged, House tells him and Annette to stop their lifestyle, but she states it is not simply about pain, rather "being completely vulnerable to another person". Harvey asks if his parents came to see him. House doesn't answer, but instead he retreats to his office, and pulls out a photograph from his desk, deep in thought over the people in the picture.