Cheng Xin and Cao Bin approach Halo City and encounter a two-week Federation Fleet blockade. Federation Envoy Blair, speaking for the Federation president, allows Cheng Xin through because Wade has claimed the final decision rests with Cheng Xin. Blair explains that Wade expanded the Halo Group during the Bunker Project, built Halo City and the circumsolar particle accelerator, then openly defied the Federation by developing curvature propulsion and declaring Halo City independent.

On the way in, Cao Bin shows Cheng Xin one coil of the enormous circumsolar particle accelerator, a vast ring of separated coils around the Sun near Jupiter's orbit. Halo City itself appears calm despite the siege, functioning like a scientific campus devoted to the dream of lightspeed travel. Cheng Xin meets the aged Thomas Wade and Bi Yunfeng, then enters a sophon-free laboratory where they demonstrate a primitive curvature propulsion device by moving a tiny piece of Cheng Xin's hair across a platform without visible mechanical force.

Wade and Bi Yunfeng argue that the demonstration proves lightspeed ships could be achieved within decades if development is allowed. Wade then reveals why Halo City is not defenseless: a small self-defense force armed with primitive-looking rifles whose bullets contain antimatter made by the accelerator. Wade says the bullets can destroy Federation warships and that Halo agents in other bunker cities also possess antimatter handguns.

Cheng Xin realizes that even if Wade never orders attacks on civilian cities, any agent could rupture a fragile space city and kill millions. Because Wade previously promised to obey Cheng Xin's final decision, Cheng Xin orders him to stop all resistance, surrender the antimatter bullets, and command all agents to disarm. Wade pleads that losing humanity's bestial nature means losing everything, but Cheng Xin chooses human nature; Wade submits, orders disarmament, and the soldiers surrender their ammunition.

After the Halo City Incident, the Federation first keeps the antimatter weapons secret, then reveals them to the public. The Halo Group is outlawed, its property confiscated, Halo City occupied, its academies dissolved, and Wade and hundreds of others arrested. Wade is convicted of crimes against humanity, war crimes, and illegal curvature propulsion research, then sentenced to death.

Cheng Xin visits Wade before his execution and gives him cigars, but the gulf between them remains unbridgeable. Wade's last words to Cheng Xin are only thanks for the cigars, and he is later vaporized by laser. Cheng Xin awakens 艾 AA, receives a small returned portion of Halo's property including a new yacht named Halo, wanders an emptied Earth with AA, learns Fraisse has died, and finally returns with AA to hibernation in Asia I for up to two hundred years, hoping to awaken after the dark forest strike.