This section starts with something of a tragedy, with Julia's family seeking her grandfather in Circadia to no avail. Just shortly after, Julia notices that her and Seth have gotten seemingly further and further apart, but after just a few words shared between them, they quickly get very close once again. On a "white night" adventure, they go together to Sylvia's house to see if she is active during the days that the normal populus sleeps. Just after this, a new tragedy was occurring at the same time. Animals had begun to panic unbelievably, causing some amount of destruction; a solar superstorm had taken place which caused the power to switch off again, with added effects. On that same day, her grandfather's old underground shelter was found, along with his dead body. The bond tightened between Helen and Julia's father, as did Julia and Seth's. However, as his sickness from their daylight endeavor became worse and worse, eventually resulting in him and his father leaving out for Mexico. He had abandoned Julia; leaving but one thing to truly remember him by, a few words they had wrote out in freshly poured concrete, "We were here." The book concludes with Julia explaining what has become of the earth, and how they plan to be remembered as a planet, in a disc filled with information about Earth and its inhabitants.
One strong theme I noticed was young love; the one that occurred between Julia and Seth. They become very close after they talk near the bus stop, and start to do a lot together. During one night, Julia and Seth had left to inspect Sylvia's house. Julia was also thinking, "We were trespassing and half in love." Later, it mentions how Julia is still thinking about him twelve years later. So, this is an example of a young love that lasts, however tragic.
As the story progresses, the economic conditions have gotten worse as time goes by. In the concluding paragraph, Julia even mentions how everyone is just preparing to die. People's outlook become very bleak, and they're just trying to survive until the end. The entire government is close to forcing people to stay indoors during sunlight hours. This leaves many people panicked, and some of the changing economic conditions can be due to how close we see some characters becoming.
One of the main driving forces in these last few chapters is just a simple, raw emotion; love. It's because of love that Julia never stopped caring for Seth. However, there are other forces at work. The slowing itself is affecting their actions as well. It's even the reason that Seth gets so sickly.