Cheng Xin and AA carry artifacts from the Earth Civilization Museum to Halo under Pluto’s weak gravity. Outside, they see Neptune and Saturn already flattened into vast two-dimensional ovals, like giant eyes in space. Inside Halo, they ask for transmissions from the devastated bunker cities and receive a feed from Europe VI, a Neptune-cluster city whose inhabitants wait in weightlessness as the advancing two-dimensional plane rises through the city.

The video shows Europe VI being converted into a precise, lifeless two-dimensional drawing. Buildings, people, ships, air, and escaping crowds are flattened in sequence, and the survivors’ attempts to flee prove useless. Cheng Xin and AA realize that the dimensional strike preserves information in exact detail but destroys all life and thickness, making the museum rescue feel nearly meaningless, though they continue because Luo Ji’s mission still gives them something to do.

On their next trip, Cheng Xin, AA, and Luo Ji see Earth collapse into two dimensions. Its structure appears as fine rings, and its oceans become an outer wreath of enormous frozen snowflakes, some larger than the Moon. The beauty of the flattened Earth finally breaks through their numbness: AA sobs, Cheng Xin weeps silently, and Luo Ji remarks that home is now only a picture.

The collapse accelerates. Mercury, the Sun, Venus, Mars, Jupiter, and Uranus fall into the plane while Pluto draws closer to the abyss. The Sun’s two-dimensional form briefly lights the planar Solar System before dimming and dying, proving that objects from the three-dimensional world cannot remain alive after flattening. Luo Ji refuses to board Halo, choosing to remain as humanity’s grave keeper, and orders Cheng Xin and AA to leave immediately to complete their mission.

After Halo lifts off from Pluto, Luo Ji reveals that Halo has the Solar System’s only tested curvature propulsion drive and can reach lightspeed. He explains that secret post-Wade research on Mercury produced curvature engines, and that the trails of lightspeed ships can lower the speed of light enough to create a black domain. Cheng Xin understands that stopping Wade cost humanity decades and perhaps its chance to build either a black domain or a fleet of lightspeed ships, leaving her crushed by responsibility.

As Halo accelerates, Luo Ji prevents Cheng Xin from returning for him and tells the women to search for the survivors who once sent a gravitational-wave message, then says farewell as Pluto and the museum enter the painting. Cheng Xin and AA become the last humans outside the flattened Solar System. With no clear destination, AA reminds Cheng Xin of Yun Tianming and his star; Cheng Xin chooses DX3906, now renumbered S74390E2, and Halo enters lightspeed toward it.