The Luminous Dead

On the colony planet Cassandra-V, Gyre Price squeezes into a deep cave system wearing an advanced full-body suit that regulates her bodily functions. A cannula in her abdomen delivers nutrition, waste is processed internally, and a heads-up display reconstructs her surroundings using sonar and infrared. The suit avoids heat-emitting lamps because of Tunnelers, massive subterranean creatures that bore through solid rock, collapsing caves and killing anyone in their path. Decades of fatal expeditions established that a single person in an enclosed suit can survive underground where teams cannot.

Gyre falsified her credentials and underwent unnecessary surgery to pass the medical exam. She has never been on a real expedition. Her sole motivation is the payout she needs to leave Cassandra-V and find her mother, Peregrine Price, who abandoned the family years ago. She expected a full support team and a sophisticated operation. Instead, she has a single handler and an uncharted cave.

Her handler reveals she owns the expedition and introduces herself as Em. Tensions escalate quickly: Em wakes Gyre with an adrenaline injection, citing the contract's authority over Gyre's bodily autonomy. While exploring near Camp Two, Gyre falls down a breakdown pile, a slope of collapsed rock debris, and discovers a dead caver at the bottom, his suit crushed and white fungus growing from his chest. Em had deliberately hidden the body from Gyre's display.

Gyre declares the expedition over. Em locks Gyre's suit, immobilizing her in total darkness. After a tense standoff, Em reveals she needs someone to reach the deepest part of this cave, that the dead man was from a failed attempt four months earlier, and that she cannot remember his name. Em offers to help Gyre find her mother if she continues. Gyre sets ground rules: no suit control or drug injections except in emergencies, no lying, and access to her headlamp at all times. She agrees to press forward.

At Camp Three, flooded passages called sumps block the route, requiring diving skills Gyre claimed on her résumé but does not possess. Em coaches her, and Gyre adapts quickly. Em then reveals she has sent 35 cavers into this system before Gyre. Twenty-seven are dead. Em claims she once went down herself as part of a team and needs someone to reach the point she reached. Gyre calculates the odds and decides to continue.

At Camp Four, the supply cache is missing. Gyre finds the body of Jennie Mercer, a caver who broke both legs in a fall and crawled under a shelf to die. She reads dossiers Em uploaded on all 35 previous cavers. Partway down the Long Drop, a nearly kilometer-long vertical shaft, Gyre slips and injures her arm. Em's face appears on her display for the first time: a dark-skinned woman in her mid-twenties, far too young to have been part of any earlier team. Em reveals the team that died was her parents'. She was six. Her mother, the sole survivor, founded Arasgain Technologies, the company that built Gyre's suit. Em inherited everything and has spent years sending cavers to where her father died, hoping to give the dead a funeral. When Gyre tries to leave, Em sedates her.

Gyre wakes furious and watches the first expedition video: a five-person team, including Em's mother, Isolde Arasgain, and father, Laurent Okeke, laughing around a campfire before an ominous rumble silences them. Em offers a contract amendment: if Gyre continues to Camp Five, Em will not sue for fraud and will find Gyre's mother. Gyre secretly activates her suit's recorder, planning to use the recordings as leverage. She signs and continues.

At Camp Five, fleshy fungal growths blanket the ground, bursting with bioluminescent spores. Gyre watches the expedition's final video: Isolde's debrief describing how teammates Halian Foster, Yao Hanmei, and Julian Flores each died, and how Laurent never emerged after Isolde laid guideline for their escape. A water recirculation exposes Gyre's suit to spore-contaminated water. She looks up and sees Isolde's face staring down from the rim above. Terrified, she flees into the sump to Camp Six.

Em returns after a prolonged absence with news: Peregrine is alive, remarried with three children, on a garden world. She offers Gyre a ticket if she turns back. Gyre refuses, reasoning that finishing the mission is the only way to stop Em from sending more cavers to die.

The final sump proves catastrophic. After navigating farther than any previous caver, Gyre is caught in a suction current and swept through an unmapped tunnel, losing all sensory input until Em administers anxiolytics, anti-anxiety medication. She finds herself in a Tunneler path, a smooth tunnel bored through rock by the creatures. The featureless passages erode her grip on reality, producing hallucinations. Her suit connects to an unknown channel that causes an involuntary spasm, smashing her spare battery. Running on her last backup, she reconnects with Em, who confesses the spores at Camp Five were not harmless: Em sedated Gyre at Camp Six to purge the contamination, and the visions were caused by spore exposure. Before cutting communications to conserve power, Em discovers Gyre's secret recording.

Gyre climbs back toward Camp Four, then descends to Camp Five to resupply. Every battery in the cache is dead from water exposure, a consequence of her earlier panicked departure. She dives to Camp Six on a failing battery. Her suit dies meters from the cache. Em remotely controls the suit's last functions to drag Gyre to a fresh battery, saving her life.

After Gyre rests, Em asks her to go back into the sump. One more try. Gyre opens the battery case, sets one battery aside, and smashes the rest. There will be no more expeditions. Em concedes.

Gyre dives toward Camp Five, but the Tunneler passes beneath the sump and cracks the rock. The water breaks through, sweeping Gyre into the chamber where the original team died. She finds perfectly preserved bodies floating in chemically altered water: Laurent, Hanmei, and two of Em's other dead cavers. Em sees her father on the feed and disappears. Alone, Gyre arranges all six sets of remains, including the bones of Julian and Halian, and builds a funeral pyre from the team's abandoned gear.

On the return journey, the Tunneler collapses the passage near Camp Three. Gyre's left arm is crushed and her abdominal cannula, the feeding-tube port in her abdomen, is dislodged. Infection spreads. Delirious, she triggers her suit's amputation system and severs her own arm. Em guides her upward through text on her cracked display. When the Tunneler appears physically, a massive iridescent worm, Gyre opens her faceplate and screams at it. Unable to support its weight in open air, the creature falls into a chasm and dies.

Gyre collapses near Camp Four, hallucinating the dead beckoning her toward the depths. Real footsteps break through her delirium. Em has descended into the cave. She takes Gyre's hand and tells her she has come to take Gyre home.

Nineteen days later, Gyre sits across from Em with a temporary prosthetic on her stump. Em gives her the key to the black box containing all their conversations, destroying her own copy. If Gyre publishes the recordings, Em will be ruined. Em hands her this power along with tickets off-world and her full paycheck. Gyre asks Em to buy two tickets: She wants Em to come with her to confront her mother. Em kneels, terrified of repeating her patterns of obsession and control. Gyre kisses her and asks her not to give up, but to try.