At the coffeehouse, Mattie and Eliza work around the clock to care for the children. As the days pass, Mattie is hungry, exhausted, and dangerously close to losing hope. Just as she begins to despair, the first frost of the season arrives. The cooler air usually means the end of diseases, so this comes as a huge relief. In celebration, Eliza and Mattie take the children outside and lay them in the cool air. With the change in temperature and the constant nursing they have received, the children quickly begin to recover. The change in weather also means that farmers begin to come back to the city to sell their products, and it becomes possible to purchase food again.
Mattie begins to ask people to send word if they hear anything about her mother. As she mingles at the market, she runs into Nathaniel, who explains that he is happy to see her and has been worrying about her. He reassures Mattie that she will surely reunite with her mother soon. As days pass, Nathaniel sees Mattie regularly and helps her with tasks related to the coffeehouse. Many of the wealthy residents of Philadelphia now begin to return to the city. Eliza and Joseph increasingly seem to think that Mrs. Cook must have died, but Mattie refuses to lose hope. Joseph begins to encourage Mattie to sell the coffeehouse. Mattie, however, knows what she wants: she announces her plan to reopen the coffeehouse and run it with Eliza as her partner. Eliza hesitates at first, but then gratefully accepts. Joseph and the children will also move into the coffeehouse so that everyone can help each other and care for the children together.
The coffeehouse reopens in early November, and business quickly starts to thrive. Mattie feels hopeful about the future and the life she is building, but she also mourns all the losses. A few days after the coffeehouse reopens, President Washington returns to the city (which, at this time, is functioning as the capital). Crowds rush out to meet him, and amidst the gathered people, Mattie catches sight of her mother. Mrs. Cook is quite frail and tells her story: as soon as she had recovered, she rushed to the Ludington farm, expecting to reunite with her daughter and father-in-law. When she realized they weren't there, she tried to set off in search of them, but she ended up relapsing. When she fell ill for the second time, she was unconscious for weeks, and it was a long time before she was well enough to return.
Mattie explains to her mother that Captain Cook has died. Mrs. Cook is grief-stricken. Mrs. Ludington explains that Mrs. Cook will never fully recover and doesn't have the strength to run the coffeehouse. She suggests that the coffeehouse be sold, but Mattie has a plan. By December, the coffeehouse is running smoothly with Mattie and Eliza doing most of the work, helped by Joseph and Nathaniel. Mrs. Cook helps with caring for the children and some of the lighter work. Mattie has plans for expansion of the business and hopes for her own life: she and Nathaniel plan to marry after he completes his apprenticeship. Although Mattie will never be the same after the trauma she has experienced, she looks towards the future with a deep sense of peace and hopefulness.
The time Mattie and Eliza spend caring for the three children at the coffeehouse is another low point for Mattie. By now, Mattie seems to have lost almost everyone she loves, and she doesn't think she can stand losing the children as well. This episode of the plot shows why epidemics cause so much emotional trauma: they create losses that occur in rapid succession, with almost no time to process or grieve. Mattie is on the verge of giving up, but she is fortunately saved by the arrival of the cold weather. While it is formidable, the epidemic is represented as a natural force and therefore governed by the rhythms of the natural world. Like a season or a type of weather, the disease will not last forever. Just as everyone had hoped, the cooler weather provides much more safety; thus, social life and economic systems such as food distribution can resume normal functioning.
As normalcy gradually resumes in Philadelphia, Mattie faces new challenges, but also new opportunities. She is under pressure to accept that her mother is likely dead, and, for many people, the next logical assumption is that she will sell the business. However, during the chaos of the epidemic, Mattie has developed a new sense of competence and self-confidence. She refuses to accept that her mother is dead, and she also chooses to believe that she can successfully run the coffeehouse herself. Because Mattie has seen strong female role models throughout her life and has further solidified her bond with Eliza during the epidemic, she trusts that the two of them can run a business together. Mattie also now feels a responsibility to ensure that Eliza and Eliza's extended family are well provided for, and she needs to care for Nell as well.
Once Mattie steps into this position of authority, she receives another stroke of good luck: she finally reunites with her mother. Mattie has now reassessed her relationship with her mother and is delighted to find her. However, it is also clear that the dynamic between them is permanently altered. Mattie now needs to be the person making primary decisions and doing the hands-on work. Mattie now has a loving and extended blended family back in her life again, but she can never go back to being the carefree child she was before the epidemic. She is now an adult who is capable of taking on responsibilities and caring for other people.
Nonetheless, Mattie does not lose sight of some of her dreams from before the epidemic. She can now trust her feelings for Nathaniel more fully because he has remained devoted and faithful to her throughout their separation. She is also able to choose a partner for herself based on her vision of what her life will look like and what she needs. Mattie will always be a visionary and someone with an adventurous spirit, but by the end of the novel, she has the maturity to use those qualities to make a life for herself and the people she cares about.