Sylveste and Sajaki are two days into Cerberus’s second interior layer, a densely packed crystalline zone they must navigate in narrow gaps. Progress is slow. They periodically extract heavy elements to replenish reaction mass. After 40 hours, they discover 10 wide vertical shafts, each approximately two kilometers across and 200 kilometers deep, which dramatically accelerate descent. Coriolis force pushes them toward the shaft walls. After descending 100 kilometers into the shafts, they are attacked. In the shaft, graphic symbols, massive Amarantin warning inscriptions, begin glowing on the walls. The symbols physically detach and close around Sylveste and Sajaki. Their suits engage automatic defenses, exchanging intense energy bursts with the animated warning-forms. Sylveste loses consciousness. When he recovers, the symbols are retreating. Sajaki’s suit has sustained critical thruster damage and is falling uncontrolled. Telemetry confirms Sajaki is 15 kilometres below and accelerating.

Aboard the Melancholia, Volyova detects that the Nostalgia for Infinity is accelerating toward them, meaning Sun Stealer has reinstated ship systems faster than expected. Volyova calculates they may just reach Cerberus before it closes within weapons range. She explains that Sun Stealer is no longer in Khouri’s mind, having jumped to the ship when Sajaki trawled her implants.

Volyova, Khouri, and Pascale, under sustained four g acceleration, discuss what Sun Stealer communicated and what the Mademoiselle showed Khouri. Volyova recounts that the galaxy was once far more populated with spacefaring cultures than it is today. The paradox, why intelligent life is so rare, is known as the Fermi paradox.

The explanation is the Dawn War: a catastrophic conflict 1 billion years ago. Its survivors, post-biological machine entities called the Inhibitors, then set about systematically suppressing the rise of new intelligent life, seeding automated devices to detect and eliminate emerging cultures. Their systems functioned for hundreds of millions of years but have been gradually failing.

The Amarantin slipped through this failing net, evolved to intelligence, and eventually sent a spacefaring offshoot, Sun Stealer’s Banished Ones, to the system’s edge, where they discovered an ancient artifact near Hades. This artifact, Pascale concludes, was an Inhibitor device. It studied the Amarantin and ultimately triggered the extinction of their civilization. The shuttle’s radar warning chimes as the pursuing Infinity closes range.

On Cerebus, Sylveste reaches the place where Sajaki’s suit crashed. He bids farewell to Sajaki, before looking inside the suit to discover that it is empty.

Sylveste reaches the third interior shell, more than 500 kilometres below the surface. Sylveste concludes Sun Stealer was piloting Sajaki’s suit the entire time and that the real Sajaki may never have been present. Sylveste decides to continue alone, feeling compelled to move forward even though he cannot be sure of his own motivations. He eventually emerges into a chamber 300 kilometers wide, in which spacetime seems to be warped. In the chamber, he stares into what seems like a gash in reality, a bright light which—to Calvin and Sylveste—could be God. The Amarantin could never have made this, Calvin reasons.

Aboard the Melancholia, the Nostalgia for Infinity opens fire with grasers. The shuttle sustains multiple strikes, losing its armor and chaff. Volyova executes a 10g evasive program and blacks out. When she recovers, the hull is nearly gone. She orders Khouri and Pascale to the spider-room and programs a final evasive pattern into the autopilot.

Khouri is caught in escaping atmosphere when the hull fails but reaches the spider-room airlock, burning her hands on the cold metal. She boards. The shuttle detonates. Pascale confirms Volyova did not make it into the spider-room and was killed. The spider-room, adrift, is falling toward Hades, a neutron star which will draw them into its deadly gravity.

Volyova survived by donning her helmet just before the hull disintegrated, drifting free, too small a target for the Nostalgia for Infinity to bother finishing off. She programs her suit to drift and wake her only if something notable occurs. She is woken when the Infinity closes in on her.

Deep inside Cerberus, Sylveste reaches the innermost chamber, 300 hundred kilometers wide, containing two objects. One is a shape-shifting jewel-like structure in constant flux. The other is a gash of intense white light. He jets toward the light. As he enters it, his suit seems to dissolve and he experiences dissolution into information: He briefly exists inside Hades itself, linked to a vast repository. He and Calvin share the experience. Sylveste retains fragmentary understanding: Hades is a transformed collapsed object engineered into a massive computer, not a neutron star, bridging past and future through causal paradoxes generated at its singularity. The crust processes information at maximum theoretical density. Sylveste then turns toward the jewel.

As they drift toward Hades, Pascale suggests that she and Khouri share a drink before their apparently inevitable deaths.

Sun Stealer’s voice speaks directly to Sylveste inside the final chamber, confirming he has been present since Sylveste returned from Lascaille’s Shroud. Sun Stealer controls Sylveste’s suit and drives him into the jewel’s interior, which is an Inhibitor device designed to lure and study intelligent organic life before triggering extinction responses. Inside, Sylveste faces geometric puzzle-assemblages designed to demonstrate intelligence to the device. Sun Stealer manipulates Sylveste’s suit arms to complete them.

Sylveste addresses Calvin directly, acknowledging that in the white light he learned the truth of his own origin, that he is Calvin’s creation in a more complete sense than he had understood, and that he cannot hate Calvin for creating him as a clone. He then activates a sequence of neural triggers that detonates the antimatter charges in his eye implants, destroying himself and the Inhibitor device from within.

Khouri and Pascale, aboard the drifting spider-room falling toward Hades, decide to drink from a discovered cabinet rather than wait in full awareness for tidal forces to kill them. Khouri next wakes on Hades’s surface, physically reconstructed and wearing a suit. Pascale, also reconstructed but now partially integrated into the Hades computational matrix, explains that they died in the gravitational tides but were recorded and rebuilt from information preserved in the gravitational flux. She leads Khouri underground into the matrix. There, Sylveste, also reconstructed, sits in a study filled with Amarantin bones and instruments, overlooking a simulated Resurgam repopulated by Amarantin running inside the matrix. He explains he passed into the matrix through the white-light portal, that his physical self is dead, and that he and Pascale intend to remain and study the simulated Amarantin indefinitely. He tells Khouri that Sun Stealer and the Mademoiselle both failed and that he believes the Inhibitor device was destroyed before fully activating, though he cannot be certain. Khouri climbs back to the surface, contacts Volyova by radio, and learns Volyova survived and that the Nostalgia for Infinity sent a shuttle to retrieve her, because Volyova warmed the captain, allowing the Melding Plague to rapidly consume and transform the ship, displacing Sun Stealer’s control. Khouri spreads her arms as Pascale instructed and the matrix projects a low-gravity bubble that lifts her into space.