This article examines the case of a Bosnian brother and sister at the center of a diplomatic dispute between Austria and the Ottoman Empire in 1852. Mara Illić had to cross the border into Austria in order to board a ship that would take her to Anatolia with the household of a paşa who had been banished. Milan called upon Austrian authorities to “liberate” Mara, whom he claimed had been enslaved when she was “forced” to convert to Islam as a young child. Austria's defense of its seizure of the girl and the Ottomans' insistence that she be returned reflect tension over sovereignty, jurisdiction, and personhood. The border brings into stark relief the conflict between different ways of conceptualizing categories like freedom and slavery, contract and coercion, confession and nationality.