Luo Ji wakes from hibernation in Year 205 of the Crisis Era after 185 years have passed. At first he is overwhelmed by a clean, personalized, elegant society whose people look confident rather than desperate, and another hibernator, Xiong Wen, tells him that humanity now believes its space fleet is stronger than the Trisolaran force and that future peace talks are likely. Luo Ji briefly takes this as proof that history has turned in humanity's favor, but he also learns that his old "spell" on a distant star is remembered only as a joke and that the Wallfacer Project has faded into irrelevance.

Special Commissioner Ben Jonathan brings Luo Ji to the SFJC's final Wallfacer hearing. The conference votes unanimously to terminate the Wallfacer Project and abolish the Wallfacer Act, stripping both Luo Ji and Bill Hines of their special status and legal immunity. Jonathan then gives Luo Ji the news he cares about most: Zhuang Yan and Xia Xia are both still alive in hibernation and can be revived later, while the ETO is thought to have been destroyed; soon after, Shi Qiang reappears, also cured and reawakened, and helps Luo Ji begin navigating the new world.

Luo Ji's first day of freedom turns into a chain of near murders. A falling flying car, an opening sewer cover, a restaurant robot with a knife, a mislabeled drug delivery, and even Shi Qiang's adaptive sofa all nearly kill him, and Shi Qiang repeatedly saves his life. A police officer, Guo Zhengming, finally explains that an old ETO program called Killer 5.2 has activated now that Luo Ji has reentered society and is manipulating networked hardware around him in an attempt to finish its mission. For safety, Luo Ji and Shi Qiang move to the surface hibernator settlements, where Shi Xiaoming and other residents explain the Great Ravine: environmental collapse, famine, repression, and mass death cut humanity down before a human-centered political reversal rebuilt civilization and later resumed a limited, sustainable space program.

Meanwhile, the Wallfacer story proves not to be finished at all. After the hearing, Keiko Yamasuki identifies herself as Bill Hines's Wallbreaker and reveals that Hines secretly made extra mental-seal devices and reversed the seal's logic, meaning the so-called Imprinted may have been given absolute belief not in victory but in defeat and escape. Hines confirms the deception and admits that he even used the mental seal on himself so that he would be incapable of repenting, leaving Fleet International unsure whether hidden defeatists still exist in important military positions.

That fear shapes the next military decision. Reawakened as part of the Future Reinforcements, Zhang Beihai is judged trustworthy precisely because he predates the mental seal, and he is assigned to act as a supervisory captain on centralized-command warships. After studying Natural Selection with Captain Dongfang Yanxu, Zhang uses his new authority to sever communications, force the crew into deep-sea state, and launch the ship at maximum acceleration. When the Asian Fleet confronts him, Zhang declares that he is not betraying humanity but preserving one stellar-class warship as a seed of civilization because he remains convinced humanity will lose the war.

Elsewhere, observers briefly lose the incoming Trisolaran probe, then recover its path by creating an enormous artificial dust cloud near Neptune and reading the wake it leaves. Later observations of the main Trisolaran fleet suggest weakening formation and an advance ship racing ahead, and Earth interprets this as evidence that Trisolaris may be preparing negotiations rather than conquest. Massive celebrations erupt, plans such as Project Sunshine imagine a future place for defeated Trisolarans in the Solar System, and a combined fleet of 2,015 ships launches to intercept the probe. Amid the jubilation, Luo Ji meets the tormented Hines, who cannot mentally accept humanity's apparent victory, while Ding Yi joins the expedition and is deeply unsettled by the probe's beautiful, seamless droplet shape.