Cytonic recap

Determined to learn where delvers come from and how to stop Winzik using them, Spensa deliberately enters the nowhere, the dimension cytonics pass through when they hyperjump. It is a place of drifting fragments of the real universe, ruled by pirate crews and slowly eroding the memories of everyone in it. Stranded and losing pieces of herself, Spensa falls in with an exuberant human explorer called Chet and is taken into a pirate crew, the Broadsiders, while Winzik's forces work openly in the nowhere on a way to weaponize delvers. Following a chain of ancient portals called the Path of Elders, she learns that the delvers were once a living civilization that transplanted itself into the nowhere and lost its individuality, and that it hears living minds as unbearable noise. Chet turns out to be a fragment of a delver that broke away and took human form. Spensa confronts the delvers at the heart of the nowhere and escapes, but M-Bot sacrifices himself to get her out, and Chet becomes part of her.

Previously: humanity survived on the caverned planet Detritus, penned there by aliens who flew unmanned drones against it. Spensa Nightshade fought her way into the Defiant Defense Force, found a wrecked advanced starfighter whose artificial intelligence calls itself M-Bot, and discovered that she is cytonic, able to hear across space and teleport a ship, the same ability her father had when he was shot down and branded a coward. Learning that the jailers were the Superiority, a galactic government that ranks species by aggression and hoards faster-than-light travel, she stole a dead alien's identity and infiltrated a Superiority fighter program on the space platform of Starsight. There she found that hyperdrives are living creatures, taynix slugs, and that the program's director Winzik meant to control the world-killing entities called delvers rather than defend anyone from them. When Winzik drew a delver to Starsight, Spensa met it mind to mind, found a lonely intelligence rather than a weapon, and persuaded it to leave. She escaped with a hoard of taynix, giving humanity hyperdrives and Detritus a shield; M-Bot lost his ship and now lives in a small drone. Winzik gained a fleet and emergency powers, and Jorgen, back home, has become cytonic himself.

Spensa decides that defending Detritus one battle at a time will never end the war, and that the delvers are the real question: where they come from, what they want, and why they hate the sound of living minds. The answers are not in the somewhere, so she goes into the nowhere itself, the dimension cytonics pass through when they jump, taking M-Bot with her. What she finds is not empty space but a strange, luminous place scattered with fragments of the real universe, chunks of ground and buildings and sky torn out of somewhere else and left drifting. Getting in proves far easier than getting out: the nowhere disorients cytonic senses, her ship does not survive the arrival intact, and she is stranded. She also learns the price of staying, because the nowhere eats memory. Everyone who lives there has forgotten most of who they were, and Spensa begins losing pieces of herself almost at once. Early on she meets Chet, a boisterous human who calls himself an interdimensional explorer, knows the fragments intimately, and offers to guide her.

Travelling the fragments with Chet, Spensa learns how the nowhere actually works: how to move between fragments, how to find the resources everyone there fights over, and how the local powers are organized. The place is run by pirate crews who raid one another for equipment and salvage while maintaining their own rough codes. Spensa is brought in among the Broadsiders, whose leader Peg sizes her up as a pilot and sets her to earning a place in the crew, alongside crewmates including Maksim and Shiver. She discovers that the Superiority is present in the nowhere too, in force and openly, mining and building under Winzik's authority for a project the pirates do not understand. Between flights, Spensa and Chet begin following something older than any of it: a chain of ancient portals scattered across the fragments, known as the Path of Elders, left by cytonics of the distant past.

Spensa earns standing among the Broadsiders by flying for them, and the crew becomes something close to a home, which is dangerous in a place that erases attachments along with everything else. Her own memory keeps thinning, and she starts using the discipline of remembering deliberately, holding on to the people she came from. Each portal of the Path of Elders she reaches puts her inside a memory belonging to a cytonic who came before, and each adds a piece to the same story: the deep history of cytonic travel, the first contact between minds across the void, and the origin of the beings the modern galaxy calls delvers. Meanwhile the Superiority's operation in the nowhere expands, and it becomes clear that Winzik is not merely studying delvers. M-Bot, cramped into a drone and increasingly preoccupied with what he is permitted to feel, starts rewriting parts of his own programming.

The Path of Elders resolves into an answer. The delvers were not born monstrous; they were a people, an ancient civilization that moved itself entirely into the nowhere and in doing so lost individuality, time and death together. What remains is a single vast awareness that does not perceive the creatures of the somewhere as beings at all, only as noise that hurts, and that lashes out at the source. The knowledge changes what victory could mean, because a delver might be reached rather than merely survived, as Spensa half proved at Starsight. It also raises the stakes of Winzik's work, since a power that could aim such a thing would need no other weapon. Spensa's loyalties are pulled between the crew that took her in and the war waiting at home, her hold on her own memories keeps slipping, and Chet's peculiarities, his gaps, his age, the things he knows that he should not, become harder to explain away.

The truth about Chet comes out: he is not a human explorer who wandered into the nowhere but a piece of the delvers themselves, a fragment that separated long ago and took on a human shape and a human personality from the minds it had touched. He has been genuinely Spensa's friend without knowing what he was. At the same time Winzik's operation reaches its object, and the confrontation Spensa has been travelling towards is no longer avoidable. The pirate crews, who have spent generations feuding over salvage, are forced to reckon with an enemy that can end all of them. Spensa's plan requires reaching the lightburst at the heart of the nowhere, where the delvers are, and doing there what she did once before at Starsight, but deliberately and against a whole awareness rather than a single visiting mind.

Spensa goes to the lightburst and confronts the delvers directly, forcing them to perceive her as a person rather than as noise, and to understand something of what they have done. She survives the encounter and gets out of the nowhere, but not intact and not alone. M-Bot sacrifices himself so that she can escape, giving up the last body he had, and Chet merges with her, becoming part of her mind and leaving her stronger, older in a way she cannot explain, and no longer entirely one person. Spensa returns to the somewhere carrying the full history of the delvers, a piece of one inside her, and the loss of the friend who had been with her since the cavern on Detritus. What she comes back to is a war already breaking: Winzik's plan is moving, her friends have been fighting without her, and the alliance humanity needs has not yet been made.

The Path of Elders gives Spensa the answer she went into the nowhere to find: the delvers were once people, an ancient civilization that moved itself wholly into the nowhere, lost individuality and time along with its bodies, and became a single vast awareness that experiences the noise of living minds in the somewhere as pain. Chet is revealed to be a piece of that awareness, a fragment that broke away long enough ago to have taken on a human shape and a human personality, and he has been Spensa's companion without either of them understanding what he was. Winzik's forces, meanwhile, have been working in the nowhere to make the delvers usable as weapons. Spensa goes to the lightburst at the heart of the nowhere and confronts the delvers directly, forcing them to see her as a person rather than as noise. She gets out, but not without cost: M-Bot sacrifices himself so that she can escape, giving up the body he had left, and Chet merges with her, becoming part of her mind and leaving her stronger and stranger than she was. Spensa returns to the somewhere carrying the truth about the delvers, a piece of one inside her, and the grief of what the trip cost, and finds her friends at war and Winzik's plan already in motion.