After arriving at Red Coast Base, Ye Wenjie is not trusted with major work at first and is kept under guard. Because of her earlier training in radio astronomy, electrical engineering, and computing, she proves highly capable once she is assigned to the Transmission Department. Ye gradually realizes that many of Red Coast's skilled officers are deliberately pretending to be less competent than they are, because anyone who becomes indispensable on a secret project may never be transferred out. As a result, Ye becomes a key technician unusually quickly.

As restrictions on Ye loosen, she studies more of the transmission system and is struck by how unsophisticated much of Red Coast's equipment seems. On Radar Peak, Commissar Lei asks for her opinion and then explains that Red Coast is supposedly an enormous microwave weapon designed to heat and destroy enemy satellites and space stations. Ye finally understands the transmitter's immense power, but before the conversation can go further, Yang Weining interrupts sharply. Ye interprets the scene as proof that Lei has trusted her on his own authority, while Yang still does not.

The next day, Ye is transferred to the Monitoring Department. There she discovers far more advanced technology: an extremely sensitive receiver cooled by liquid helium, larger computer systems, interactive programming terminals, FORTRAN, and databases. In another private talk, Lei explains that Red Coast originally brought Ye in because her research on solar activity might help solve interference caused by solar flares and sunspots, but that her abilities convinced him to give her broader responsibilities. Lei says that his trust in Ye has so far been personal rather than institutional and tells her he hopes one day to call her "Comrade Ye," which moves her deeply.

Even with Lei's support, Ye struggles more in Monitoring than she did in Transmission because her computing knowledge is outdated and her access remains limited. Yang supervises her closely and treats her with increasing hostility. At the same time, Ye notices contradictions that make Red Coast's official mission harder to believe: the base intercepts poorly encrypted KH-9 satellite photographs of sensitive Chinese targets, yet Yang abruptly stops monitoring that valuable source; on another occasion, Ye sees planned transmission frequencies that are below microwave range and could not produce the heating effect Lei described.

Eventually, Ye is summoned before the base leadership and expects Lei to be punished for confiding in her. Instead, Lei reveals that the anti-satellite explanation was itself a cover story. He says that Yang repeatedly sought approval from higher authorities to tell Ye the truth so her abilities could be used fully, and the request has now been granted. Left alone with Ye, Yang makes clear that learning Red Coast's real purpose will extinguish her remaining hope of ever leaving the base. Ye accepts that cost and agrees, and on a windy early-summer evening Yang begins to explain Red Coast's true nature.