In Year 20 of the Crisis Era, Rey Diaz and Bill Hines are awakened because key technologies have finally arrived. Humanity has advanced quickly through massive investment, but only in engineering; fundamental physics is still blocked by the sophons, so everyone knows this technological surge must eventually slow. Keiko Yamasuki reunites with Hines and shows him the extraordinary supercomputer she has helped build, along with the Resolving Imager’s holographic map of her own brain. Using this system, their team studies how the brain makes judgments and discovers that critical thinking is a dynamic pattern spread through neural activity rather than a fixed physical location.

That research takes a dangerous turn when a volunteer test subject, after an intensified scan on the proposition “Water is toxic,” begins sincerely believing it. Hines repeats the experiment on himself and suffers the same effect, proving that the team can force the mind to accept a conclusion without normal reasoning. Hines and Keiko Yamasuki realize they have found a way to implant belief directly into the brain, which they name the mental seal. Hines presents it to Chang Weisi as a possible cure for defeatism in the space force, but Chang Weisi rejects imposed faith as too close to destroying free thought.

At a PDC Wallfacer hearing, Hines’s proposal shocks the delegates, who denounce the mental seal as the darkest form of thought control. Hines therefore reframes the idea as strictly voluntary self-application, arguing that desperate wartime conditions justify sacrifice. After long debate, the assembly allows a tightly supervised “Faith Center,” limited to space-force personnel and a single approved proposition: that humanity will defeat Trisolaris. The center opens to empty curiosity, then slowly receives genuine volunteers. A former officer named Wu Yue comes seeking spiritual peace rather than victory and must be refused, but soon young space-force officers undergo the seal and emerge with visible calm and certainty. As more volunteers arrive, Hines concludes that he and Keiko Yamasuki have finished their work and should hibernate until the Trisolaran probes approach; yet as Keiko Yamasuki enters hibernation, she suddenly shows mute terror, as if she has realized something too late to say.

Meanwhile, fusion progress produces the glowing “nuclear stars” of reactor tests in orbit, and improved computing finally makes stellar hydrogen bombs practical. Rey Diaz pushes to test them on Mercury, claiming he wants an underground base on the innermost planet as a final defensive bastion. The PDC reluctantly allows the test, and the explosion blasts out a vast crater and throws enough debris into orbit to give Mercury a thin ring. Soon after, Rey Diaz’s Wallbreaker arrives and reveals the real logic behind the plan: Rey Diaz meant to stockpile immense numbers of stellar hydrogen bombs on Mercury, use them to slow the planet until it falls into the sun, and trigger a cascading solar catastrophe that would strip Earth and the other planets and doom both humanity and Trisolaris. The Wallbreaker also argues that the plan is fatally impractical because humanity cannot build enough bombs. Enraged at being exposed and mocked, Rey Diaz attacks and nearly strangles him.

At the next hearing, several major powers move to halt Rey Diaz’s plan and prosecute him. Rey Diaz responds with a bluff, claiming that his wristwatch is a dead-man’s switch tied to a hidden trigger in New York, so harming or arresting him could cause mass death nearby; the threat is enough to secure his release and a flight home. Once airborne, Rey Diaz admits privately to Garanin that the device was only a transmitter and the threat was false. Back in Caracas, however, public hatred overwhelms his protection, and a mob stones him to death beneath a statue of Simón Bolívar. The chapter closes by sweeping across later years: Chang Weisi retires and dies, Say devotes herself to the Human Memorial Project, Wu Yue dies unhealed, many veterans of the old world pass away, and the generation that remembered humanity’s former Golden Age disappears into history.