The threat of the loss of his mill is a very bitter prospect for Mr. Thornton. This is, of course, partly the dread of losing his livelihood and the company he built from the ground up. In addition, Mr. Thornton sorely regrets the fact that it might be now, when he and his workers have finally come to an understanding- and liking- of each other, that he might be forced to close down his mill.
This new sense of connection has been facilitated a great deal through John's sometimes fractious relationship with Nicholas Higgins; despite their differences, they have formed a mutual respect and even liking for each other. They also find that the two of them have certain things in common, one of these being an interest in Margaret Hale. Nicholas stops his employer one day and asks if he's heard anything of Margaret lately. Mr. Thornton says that he hears of her through her agent, as she is now his landlord; she is well and with friends in London. Something in his voice and look makes Nicholas suspect John's feelings for Margaret, so he decides to probe a little deeper, asking if Margaret is getting married. His face darkening, Thornton says that there is some talk of her possibly marrying a friend of the family. Nicholas then asks if the "young gentleman" got clear and, at Mr. Thornton's mystified look, clarifies that he means Margaret's brother, Frederick. Nicholas explains that Frederick had come to Milton secretly at the time of his mother's death and that he and Mary knew because she was working for the Hales at that time. John quickly puts two and two together and realises what happened the night of Leonard's death and why Margaret lied about it. Despite the fact that he will never see her again, Thornton is relieved to know that he was not mistaken about her character. It is the one bright spot in his life at present.
Now that the decision to close Marlborough Mill has been made, John has to give up his lease for both the mill and the adjacent house. To do this, he must go to London to speak to his landlady- Margaret- or her lawyer, Mr. Lennox. As John prepares to do so, word sweeps through the town that his brother-in-law's speculation has, against all odds, succeeded and he has made a large fortune.