After returning home from Rome, Dorothea contemplates the portrait of Casaubon's ill-fated aunt and feels a reluctant kinship with her because she experienced marriage difficulties. Brooke comments to her that Casaubon looks pale. Celia tells Dorothea that she is engaged to Sir James Chettam. Casaubon thought he had found everything he wanted and more in Dorothea: a ready helpmate with "the purely appreciative, unambitious abilities of her sex." He wanted a wife who would admire him uncritically, but he doesn't experience the bliss he expected.

Two letters from Ladislaw arrive, and Casaubon reports that Ladislaw suggests that he would like to visit Lowick Manor. Casaubon tells her he must decline because Will's presence would distract him from work. Irritated, Dorothea responds that she could not take pleasure in anything that would displease him. Her evident headstrong nature makes Casaubon nervous. Casaubon begs her to drop the subject. They work for a short while until Casaubon collapses with some kind of fit. They send for Sir James, who suggests that they have Lydgate examine Casaubon. Sir James regrets anew that Dorothea married herself to such an elderly man.

Lydgate advises Casaubon to be satisfied with moderate work and frequent relaxation. In private, Dorothea begs him to tell her if she is to blame for Casaubon's heart attack. He tells her that she is not guilty. He states that Casaubon could live another fifteen years only if he is careful to follow Lydgate's advice. Dorothea reads Ladislaw's letters. He writes that he plans to return to England. He wants to deliver Naumann's painting of Casaubon in person. She requests that Mr. Brooke write Will and tell him not to come to Lowick because Casaubon is ill. Brooke invites Will to come and stay at Tipton Grange without telling Dorothea.

Selina Plymdale, Ned Plymdale's mother, tells Mrs. Bulstrode that she believes Rosamond and Lydgate are secretly engaged. She is annoyed that Rosamond rejected Ned in favor of a newcomer in Middlemarch. Mrs. Bulstrode visits Rosamond to ask her about her secret engagement. Rosamond informs her that she has not become secretly engaged to Lydgate. Mrs. Bulstrode warns Rosamond that Lydgate is not wealthy and that the medical profession is not likely to make him wealthy. Rosamond tells her that she is sure Lydgate has good connections, so he must not be poor.

Mrs. Bulstrode questions her husband and learns that Lydgate has said nothing indicating plans to marry soon. Mrs. Bulstrode hints to Lydgate that Rosamond has gotten the wrong idea. Lydgate resolves to stay away from the Vincy household. Rosamond becomes very unhappy. However, one day he has to go see Mr. Vincy because Featherstone's health is beginning to fail. Vincy is not home, but Lydgate sees Rosamond, whose obvious heartache touches him. She begins to cry, and he kisses her tears away. He leaves the Vincy household as an engaged man. He asks Mr. Vincy's permission to marry Rosamond. Vincy is so delighted that Featherstone is on the brink of death—he hopes Fred will inherit his estate—that he gives his blessings.

The news of Featherstone's imminent demise brings all of his relatives to Stone Court. They all watch one another suspiciously and quarrel over who deserves to get Featherstone's money and land. Featherstone refuses to see any of them. One night, Featherstone tells Mary that he has written two wills, and he plans to burn one of them. He asks her to open his iron chest and take out the will inside it. She refuses. He is too weak to do it himself, so he tries to bribe her. Mary says she won't compromise her reputation. Featherstone dies that night clasping his would-be bribe money and the key to his iron chest.