At a bike race, two kids are looking for a good spot to watch – one of them, Matthew, needs an inhaler. He spots his hero, Jeff Forster, who collapses and several other bicyclists plow into him.
A bored House is kicking back in his office when Stacy comes in and informs in he needs to get his reapplication forms filled out. Cuddy interrupts to announce he has a patient – the world-class cyclist who collapsed earlier, Jeff. Jeff has respiratory problems and House figures it's enhancement drugs, specifically erythropoietin (EPO). House visits Jeff who is there with his manager Moira, and Jeff admits he gives himself transfusals of red blood cells. Jeff reveals his whole enhancement history and why he does it to win, but stopped it for the bicycle race.
House meets with his staff for differential diagnosis but none of Jeff's treatments correspond to his respiratory distress. House suspects he has an air embolism as a result of his many injections and orders a test. Cameron isn't thrilled that Jeff is taking advantage of his fans and then they spot the embolism.
House is having lunch with Wilson when Stacy comes in with her husband. House and Mark spar briefly and Wilson reveals Mark is going through group therapy, giving House something to think about. Meanwhile, Chase is extracting the air bubble from Jeff and gets it out but Jeff starts drooling uncontrollably.
Chase concludes it's muscle fatigue and House figures he might have hit a nerve but nothing is definite so House calls for more tests before heading out to a session…the session Mark is in. Despite the head doctor Louise Harper's efforts, House stays on and she suggests he and Mark work things out. Cameron prepares for a muscle biopsy and it becomes clear she has issues with Jeff's use of drugs. In session, things start off well but things break down and Harper sends House to a different group.
The tests prove negative for all suspected problems – House wonders why Jeff's tests are all normal then suspects encephalitis. Jeff's manager confronts Cuddy with Jeff's (relatively) slow treatment regimen and makes a donation to speed things up. During the new test, while Jeff admits he took advantage of one young fan he goes into respiratory arrest again, with his red blood count dropping.
House concludes that either Chase screwed up, or Jeff has cancer, and orders more tests. While meeting with a clinic patient coming off smoking and suffering from diarrhea, Stacy comes in (repeatedly) to give House grief over his messing with Mark in group therapy. She tells him to let it go, while House figures the patient is being poisoned by his sugarless gum.
Wilson is running cancer tests on Jeff while he wonders if he did it to himself and his manager figures it's a staff screw up. Later Wilson meets with Cameron after he's figured out she calling the newspaper and finding out if what Jeff did was cheating. Wilson admits that he cheated on his wives but always came clean with them.
The tests show that there's no cancer and Chase didn't screw up. Cuddy comes in with Stacy – the story about Jeff has gone public and Stacy is going to have to watch them since they figure there's a leak. House wonders why someone would leak information about Jeff's supposed cancer and confronts him, taking out his breathing tube to get him to talk. House figure he's been using a drug, EPO, and Jeff claims he hasn't used it for years. Traces disappear after six hours so they can't test, and House figures Moira leaked the info to the press so Jeff could come back from cancer and improve his image. Moira still denies she gave him EPO, and Jeff fires her.
Jeff starts to recover as they treat him for EPO but then has a relapse. Foreman orders a transfusion and House orders them to scan Jeff's neck. Then House chats with Wilson about Stacy, and Wilson suspects he's "having fun" and warns it won't end well for anyone. The staff finds a thymoma, one that causes PRCA resulting in anemia. Transfusions and hyperbaria keep the symptoms down, so Jeff's been treating himself all this time, until he stopped the transfusions and hyperbaric treatments for the marathon. House reveals Mora is innocent and with a quick injection cures Jeff…temporarily.
House drops in to meet with Stacy and want to know if she hates him or loves him. She admits she hates and loves House…and loves Mark. They conclude there's not much they can do but live with it. Wilson chats with Cameron who is watching Jeff give an interview – she's not impressed with how he got away with cheating. Cameron reveals she fell in love with her husband's best friend Joe, but she didn't sleep with him. Later House cons a janitor into letting him into the group therapy room to get at Stacy's psychiatric records, while Wilson and Cameron consider their past affairs.