With the protection offered to Missions under Spanish law, the Jesuit missions have been safe. However, the Treaty of Madrid (1750) reapportioned South American land on which the Jesuit missions were located, transferring the area to the Portuguese, who allowed slavery. The Portuguese colonials seek to enslave the natives and, as the independent Jesuit missions might impede this, Papal emissary Cardinal Altamirano, a former Jesuit priest, is sent from the Vatican to survey the missions and decide which, if any, should be allowed to remain.