M5, T9: A gun-wielding man from the waiting room at the Princeton-Plainsboro clinic takes House, Thirteen and several patients from the waiting room hostage in Cuddy’s office. The man claims to be sick with a long undiagnosed illness and demands medical attention from the best doctor in the hospital, threatening to kill any hostages necessary along the way. With a room full of already sick patients, House must use them as guinea pigs to assure the hostage-taker that the medications he is administering to him are legitimate. As Cuddy and the rest of House’s team communicate with House over the phone to run tests and offer possible diagnoses, they ponder the possibility that the hostage-taker has nothing physically wrong with him and that everyone in Cuddy’s office could wind up dead. With one hostage already shot, Thirteen wagers her own already diminished health as she simultaneously receives the experimental treatments the hostage is receiving. Her life lies in danger as House’s own determination to diagnose the hostage-taker threatens to thwart the SWAT team’s plan to put an end to the standoff.