The Legend of the Female Stranger

A full moon hung over Old Town Alexandria when a mysterious ship arrived. Two people emerged from the ship, a man and his wife. The couple made its way west on Cameron Street, toward the City Hotel.

Mrs. Wise immediately called for a doctor to look after the woman, who was obviously suffering from an extended stay at sea. Everybody in the tavern speculated that they arrived from the West Indies, a vermin-infested area that was infamously spread disease.

The husband and wife were shown to Room 8, where the woman's condition continued to deteriorate. Despite being attended by one of Alexandria’s doctors, an unlicensed practitioner who practiced the medical arts for one dollar per visit, the woman continued to grow sicker every day. Eventually, the husband summoned the doctor, hotel staff and even the owner’s wife to Room 8 to ask a very unusual request: He asked that everyone present swear an oath never to reveal their identities.

The rest of the story at this link. Metafilter speculation thread here. Biography of Aaron Burr's lost daughter here.