Humanity tries to get back to normal after the events of the Great Resettlement, Cheng Xin hibernates for 5 years to give time to restore her vision. During that time AA rapidly builds up their business.
During the intervening years, humanity starts to question the validity of the Dark Forest theory itself, thinking that the Trisolarans might be suffering from “delusions of cosmic persecution.” This thinking is quickly reversed as Earth sees one of the stars of Trisolaris get hit with a photoid attack and destroys Trisolaris itself with only 1/1000 of the population able to survive.
Sophon invites Cheng Xin and Luo Ji to tea at her house again. During the now famous “Conversation of the Way of Tea” Sophon reveals that dark forest strikes are done in the most economical fashion, for example on Trisolaris no reconnaissance was done, the attacking civilization just used the power of the star against its own system. Escape is the only means of survival.
During the conversation, Sophon has to be careful about what information they’re willing to give out, but out of respect to Luo Ji, she agrees to answer one question entirely truthfully. Luo Ji asks if there’s a way to broadcast a “cosmic safety notice”, to which Sophon responds “Yes”
While humanity splits into factions on how to send such a safety message, Cheng Xin becomes despondent to the point where she contemplates suicide. Sophon has another message for her that will change the course of history, “Yun Tianming would like to see you.”
Cheng Xin travels to outer space for the first time for the meeting to be conducted over real-time video communication via sophon. She is warned that if there’s any “unacceptable” conversation topics or recording devices, the Trisolarans will destroy the ship that she is on.
When they finally meet, Cheng Xin is surprised to see Yun Tianming as a healthy looking farmer, thanks to the seeds that she sent along. Cheng Xin tries to extract what information she can, but the Trisolarans quickly warn her and realize that she is not going to get any actionable information. It is then that Yun Tianming suggests that they remember the fairy tales that they used to tell each other (despite the fact they only met in college)
Tianming then goes on to tell an elaborate story about the Storyless Kingdom, where a princess is set to take the throne, but her brother seizes power by having his painter paint his family into paintings that makes them disappear from the kingdom. The princess is protected by her Aunt and an army captain as they make their way to see her other brother stranded on an island that is separated by a sea filled with dangerous fish. They make their way to the island using the magical soap of the far away land of He’ershingenmosiken to mollify the fish. The prince and princess return to the castle, defeat their brother, and the princess takes the chance to travel the world while her brother rules the kingdom.
Of course, the fairy tale was wholly invented by Yun Tianming as a means to disclose information vital for the survival of humanity wrapped in the metaphors of a fairy tale to not raise the suspicions of the Trisolarans and protect both Chang Xin and Tianming. Humanity tries to decipher them, but ultimately cannot come to an agreement on their meaning, so instead embark on a new project to try to save humanity, the Bunker Project, whereby they intend to build city-sized ships behind Jupiter and beyond that will protect the people from a photoid attack towards our sun.