A family is playing bridge when the young girl Amy begins to have dizzy spells and complains of stomach pains. Her father Henry takes her aside then begins to have some kind of seizure then freezes up. Then he snaps back to normal without realizing anything happened.
Henry is at the clinic and Foreman is examining him for what he describes as an absent seizure. Henry says he's had no previous symptoms and Foreman suspects testicular cancer, but House points out the flaws in the theory. House notes a possible abscess in his brain, or possibly a STD, and orders treatment because if the tests are right, there's nothing they can do.
House meets with Wilson and, noticing he's buying chocolate, thinks he's having an affair despite Wilson's denials. Then House has to deal with a clinic patient, Tony, who has a thing about cows and wants a tranquilizer. Foreman talks to Henry who says it can't be anything sexual as he hasn't had sex since his divorce. Foreman believes Henry and wants to treat him for lymphoma – House figures Henry is lying and talks to him when the daughter Amy isn't in the room. Henry reveals he did have sex during a cheese-tasting festival with his wife after she had several affairs, but didn't want Amy to know. House starts giving him STD treatments and Amy returns, and House and Henry lie to cover. But then Henry starts choking and coughing up blood and their forced to intubate.
The new symptoms disprove lymphoma or STDs, and the staff run through other possibilities. House notices Henry's had acid reflux then takes him off the air. House figure it's unpasteurized goat cheese with bacteria, which multiplied in his stomach. House gives him treatment for it until the tests come back then has another verbal sparring match with Wilson over his supposed affair. Henry goes into cardiac arrest and House is called in – the test is positive but they got to it too late and he won't last the week.
House goes to the transplant board but they're reluctant to approve due to Henry's age of 65. Foreman gets to give the news that the board voted no on the transplant. House admits he agrees with the board but still signs Cameron's letter of appeal. Then he meets with Tony again, who supposedly got kicked in the ankle by his cow. House is skeptical of his claim even though Tony agrees to any (painful) tests necessary. Cameron and House work to find a possible heart donor – they up with a 40 year old woman from a car accident, one with a bad heart that they can still use rather then nothing at all.
Passing him off as the consulting physician, House meets with the woman's husband, Ronald, and checks out her health but she had a fever and stomach ache. House lays it out – he needs the wife's heart. The donor committee declares her heart non-viable but Foreman notices the medical report says she has Hepatitis-C. House disputes the diagnosis based on the fever and stomach pains. Ronald orders the ventilator to be shut down but House keeps it going and appeals to Cuddy. Ronald wants her to be shut down and isn't thrilled with how House deceived him, but House needs the extra time to determine if the heart is usable. Amy confronts Ronald and thanks him for his donation, and House appeals to Ronald to help her despite his feelings for House. Ronald punches House in the gut…then agrees to let Henry have the heart.
Now House and his staff have to identify the illness and run her through a MRI as Ronald looks on. They find a cyst but it's not a gall bladder infection – House suspects a liver infection. House orders 20 times the normal dosage since they don't' have to worry about patient viability. Then it's back to Tony, and House has figured from the blood tests that he eats cows. Tony reveals that he needed the tranquilizers to deal with sexual arousal caused by his mother – House gives him the medication. Then he talks to Wilson who hypothetically agrees he might be having an affair and needs House as someone to have a serious conversation with – House blows him off.
Laura's heartbeat is irregular and House orders them to stop the medication rather then render the heart unusable. Ronald changes his mind and now insists they have to use her heart to save Henry. It's back to differential diagnosis and they can't do a biopsy. Cameron suspects a toxin that targeted the liver and House goes to her house with Ronald. House finds several possibilities, while Henry has further heart problems. House finds hair dye, sleeping pills, and diet pills, all suggesting she lied to Roanld. None of them explain the fever, but Cameron finds photos of naked teenage boys in her school desk. House figures she may have had gonorrhea which caused scarring of the liver. The tests prove positive and they start giving medication, but it'll take 4-5 hours and Henry doesn't have that long.
House goes ahead with the transplant, hoping to treat Henry for gonorrhea once they've got him away from deaths' door. House lies to Ronald long enough for them to get the heart. Cameron prepares to give Ronald the news but he reveals Laura was distant and he had a one-night stand where he got gonorrhea, which he thinks he gave to her and caused her death. Henry revives and his reunited with ex-wife and it's a happy reunion of sorts.
At home, House is making supper when Wilson shows up – he's been kicked out by his wife and needs somewhere to stay. He reveals that it's his wife who was having the affair because he wasn't spending enough time with her. And House has a new roommate.