As the lockdown is occurring, the team discovers a rash on the girl's armpits inconsistent with smallpox, causing House to change his diagnosis.
Dr. Dave Broda, the CDC official overseeing the case, blocks House's team from contact with the patients to make a new diagnosis, so they turn to the only other evidence they have: the captain's logs from the wrecked slave vessel.
When Broda refuses, House risks his own life by entering the containment room and administers the treatment to save the patient.
She notes that a cat on the ship had lost all his fur and then died, strong evidence for rickettsialpox, a disease easily treatable with antibiotics.
When House successfully spots eschars on the body, Broda orders that the daughter be treated with doxycycline, saving her life.
In a subplot, Wilson and Sam reexamine their relationship while treating a young chemotherapy patient whose mother gets locked outside of the hospital during the lockdown.