Cheng Xin and AA continue discussing Yun Tianming’s fairy tales under sophon surveillance, using ordinary conversation and eye signals to avoid revealing their conclusions. Cheng Xin realizes that the snow-wave paper confirms the earlier soap-and-paper-boat clue: the stories point to curvature propulsion, meaning Trisolaran ships use space curvature drives and humanity now has a clear technological direction for lightspeed flight.

At an IDC meeting two days later, the committee unanimously accepts this interpretation. The interpreters identify Tianming’s hidden-message system: dual-layer metaphors, in which one metaphor points to a simpler image that then points to the real intelligence, and bearing-coordinate metaphors, which confirm and disambiguate the intended meaning. Cheng Xin is moved by Tianming’s lonely effort to create many fairy tales and conceal strategic hope within three of them.

The IDC next studies the fairy-tale umbrella. Cheng Xin, Bi Yunfeng, and Cao Bin recognize it as a centrifugal governor for steam engines, suggesting constant-speed regulation. When paired with Prince Deep Water’s unchanged apparent height and the bubble-tree description of massless, fastest bubbles, the umbrella points to the speed of light and possibly to lowering it, though the exact strategic use remains unclear.

A linguistic breakthrough comes when Palermo’s Norwegian girlfriend identifies He’ershingenmosiken as a distorted combination of Helseggen and Mosken, two old Norwegian place names. Cheng Xin, AA, Bi Yunfeng, Cao Bin, Palermo, and others travel to Mosken Island, where the old lighthouse builder Jason directs them not to the lighthouse but, almost accidentally, to the Moskstraumen maelstrom. The group enters the whirlpool in Jason’s boat, experiences its terrifying descent, and is rescued by helicopter before the boat is destroyed.

The maelstrom gives the interpreters the missing clue: a black hole. During the flight to Oslo, Cao Bin realizes that if the speed of light in the Solar System were lowered below the Solar System’s escape velocity of 16.7 kilometers per second, light itself could not escape and the Solar System would become a sealed black domain. Such a black domain would serve as the cosmic safety notice by proving to outside civilizations that humanity could not leave or threaten the universe.

Most of Tianming’s clues now fit together: curvature propulsion offers escape, while the black domain offers safety through self-sealing isolation. However, the paintings of Needle-Eye remain undeciphered, leaving one elegant and disturbing mystery at the foundation of the three stories.