House accepts the case but is bored until they figure out Kalvin is showing all the signs of fighting back against the AIDS but is still getting worse.
House suspects the strength of Kalvin's immune system fighting back is causing his new symptoms, and orders more tests.
House then prepares to kill Stacy's rat so he can get her to reveal his feelings and get her fired, but notices its odd behavior.
Cameron is given treatment for the possibility of HIV while House considers the new symptom, a ruptured blood vessel in the lung.
While she and Chase go off to check Kalvin's apartment, House runs the rat's odd behavior past Foreman to get a diagnosis.
Cameron mentions that legal might check her out for HIV testing and treatment and accuse her of using drugs to get out of paying her bills.
They also find Kalvin's photos of broken 1930s fluorescents that contained beryllium, which can inflame the lungs and inhibit breathing.
As Cameron conducts her test and reveals she hid his drugs, Kalvin suggests that HIV might actually loosen her up since she no longer has to play by the rules.
The next day Cameron shows up for work as House arrives with his rat (nicknamed "Steve McQueen") and quickly figures out she was using.
The staff check over the new information – Kalvin lied and his mother died because she needed a kidney and he was the only donor, but had HIV.
It soon becomes clear to everyone Cameron and Chase slept together, and the tests show that Kalvin has terminal cancer with no chance of a cure, and they prepare to pinpoint its location with a biopsy.
Michael takes a swing at him and then House cold cocks him in the gut, initiating anaphylactic shock and confirming his diagnosis the hard way.