On a weekend morning, Wang Miao goes out to take photographs but cannot regain his usual calm. Troubled by Ding Yi's description of physics losing its foundations, Wang keeps thinking about the Frontiers of Science ideas of the shooter and the farmer: apparent laws may be accidental patterns or traps mistaken for truth. This makes the city itself feel unstable to him.

When Wang develops his film at home, he finds a mysterious series of numbers on every negative. By comparing the images with his shooting log, he realizes the numbers form a countdown that decreases exactly with elapsed time. He tests the phenomenon repeatedly with new rolls, including shots taken with the lens cap on, and concludes that neither ordinary light nor a normal camera defect can explain it. When Wang gives the same camera to his wife and later compares results, he discovers the crucial fact: the countdown appears only on photographs that Wang himself takes, not on images taken by his wife or son.

Unable to explain the targeted phenomenon, Wang takes the film to Shen Yufei. At Shen's house, he notices she has been playing a game on 3body.net, which deepens his suspicion that the Frontiers of Science is tied to something larger. After hearing his story, Shen does not explain the countdown. Instead, she asks about Wang's nanomaterials project and repeatedly tells him to stop the research. As Wang leaves in frustration, Pan Han arrives and warns Shen not to force "their hand," suggesting that an organized group is behind the intimidation.

That night, the countdown escalates from appearing on film to appearing directly in Wang's vision. It remains visible with his eyes open or closed, against darkness, city lights, and even the sun, and an eye examination finds no physical cause. Exhausted and terrified, Wang goes to his laboratory still seeing the numbers. There, while hearing about serious maintenance problems in the reaction chamber, he remembers Shen's instruction and orders the nanomaterials experiment stopped immediately. The effect is immediate: the countdown freezes and then disappears.

After confirming that stopping the project ended the phenomenon, Wang calls Shen. He accuses her side of using elaborate illusions to obstruct technological progress, while Shen stays cryptic and warns that Wang is facing the same danger that destroyed Yang Dong. When Wang challenges her to demonstrate this power on a larger scale, Shen accepts. She sends him a Morse code chart, instructs him to prepare to observe the cosmic microwave background, and warns that if Wang restarts the project, the countdown will resume and, on the appointed night, "the entire universe will flicker" for him.