It is in chapter two that we find out that Miss Mary Finch, before her death, said in her will that she had granted freedom to both Isabel and her sister, Ruth. This is something that she assumes was known about because when she approaches Pastor Weeks to ask him what she and Ruth should do and where they should go, she is shocked to hear him tell her that actually they don't need to go anywhere because Mr. Robert is their new master and that he will look after them and provide for them. The way in which Mr. Robert has so clearly destroyed or hidden the will that says Isabel and Ruth are free only serves to highlight the powerlessness of Isabel's situation.
At the end of the chapter, this feeling is made even worse when Isabel realises that she and her sister are to be sold as quickly as possible by Mr. Robert, who wants to liquidate his aunt's assets and return back to his home with the money. Therefore, we are told that Miss Finch has already freed Isabel from slavery, but that her good-for-nothing nephew does not choose to honour this promise, seeking material benefits over fulfilling the will of his dead aunt.