In Ascension

Leigh, a Dutch marine biologist, grows up in Rotterdam in a household defined by silence and violence. Her mother, Fenna, is a brilliant but withdrawn mathematician who has debilitating migraines. Her father, Geert, a frustrated architect who resented his job as a hydraulic engineer, subjects Leigh to sustained beatings beginning around age nine, though only when Fenna is at work. Her younger sister, Helena, is largely spared. Fenna never confronts the abuse, retreating into her work, though she comes wordlessly to Leigh's bedside during painful growth spurts, massaging her aching limbs in the dark. These silent acts of care form the deepest bond between mother and daughter.

Leigh finds solace in water. Swimming alone in the Nieuwe Maas river at age ten, she plunges beneath the surface one desperate autumn afternoon and perceives the teeming microscopic life filling every cubic millimeter around her, recognizing she is not separate from it but immersed within it. This encounter transforms her. She pursues marine microbiology, studying archaea, single-celled organisms among the earliest life forms on Earth. During a research placement in the Azores, she learns that NASA has announced a radical propulsion breakthrough capable of increasing spacecraft velocity by a factor of 10,000.

In the final year of her doctorate, Leigh joins the research vessel Endeavour as service staff on an expedition to a newly discovered hydrothermal vent in the mid-Atlantic. She befriends Amy Delacroix, a French-Canadian engineer from NASA's Jet Propulsion Laboratory, and Stefan, the expedition leader, who becomes a mentor figure. Sonar returns suggest the vent reaches 36 kilometres deep, three times the Mariana Trench. Leigh volunteers for the first dive and undergoes a visionary experience, perceiving cascades of bioluminescent life. All five divers fall ill with fever and delirium yet feel compelled to return to the water. Amy's autonomous submersible, Scintilla, descends to record-breaking depths before contact is lost. Stefan, increasingly consumed by the vent's pull, vanishes with his scuba gear and is never found.

More than two years later, Leigh accepts a job in California with ICORS, the Institute for Coordinated Research in Space, established to exploit the propulsion breakthrough. The offer came through Amy. Leigh's task is to develop algae-based food systems for long-duration space missions at a lab near the China Lake military station. Her supervisor, Uria, a Russian-American astrophysicist serving as Projects Director, becomes both mentor and surrogate mother figure. Leigh discovers that Uria has authorized splicing a gene from archaea recovered during the Endeavour expedition into one of her algae strains without her knowledge. She suspects the gene may relate to the singular symbiosis between archaea and bacteria that created eukaryotic cells, the basis of all complex life.

Meanwhile, Helena reports that Fenna has fallen at home and shows signs of cognitive decline. The sisters arrange care from a distance, but Leigh cannot visit, consumed by her work. She begins sending Fenna daily audio recordings, which her mother plays at night to fall asleep.

After Leigh gains higher clearance, Uria reveals two connected secrets. First is Datura, a 1.3-kilometre interstellar object bearing massive carved lines and self-referential oval patterns suggestive of language, with non-gravitational acceleration and no outgassing, behaviors inconsistent with any known natural object. Datura has since vanished. Second, Goldstone Observatory detected a nineteen-digit number repeated 3,042 times, traced to Voyager 1, the 1977 space probe presumed dead. The signal came from a position near the inner rim of the Oort cloud, a vast shell of ice and rock at the solar system's edge, impossibly far beyond Voyager's own propulsion capability. Uria concludes that the same entity moved Voyager and sent the signal. Leigh draws a further connection, noting that the propulsion breakthrough's engineers reportedly developed their discovery while experiencing fever and visions of spinning orbs. The mission, Proscenium 1, will send a crew to Voyager's position as the first act of two-way extraterrestrial communication.

Uria asks Leigh to join the California backup crew alongside Tyler, a structural engineer and pilot, and Karius (K), a Serbian-born optical systems designer. During a KC-135 parabolic flight over the Sea of Cortez, Leigh experiences weightlessness for the first time and is overwhelmed as bodies lift from the floor and her crewmates' faces open into expressions of pure joy. An eco-terrorist attack disables Crew 1 at the Xichang spaceport in China, and when Crew 2 in Kazakhstan also cannot fly, Leigh's team is activated. During isolation at Kourou spaceport in French Guiana, Dr. Allen, the chief medical officer, tells Leigh that bird die-offs and turtle migration failures may be linked to trials of the alien-derived propulsion technology. Leigh manages one emotional phone call with Helena, unable to reveal details but asking Helena to tell Fenna she is loved.

Nereus is a compact, sealed craft with three berths, a garden module for the algae, and a detachable re-entry capsule. Its propulsion system, derived from Datura's technology, operates autonomously and cannot be directly observed without ceasing to function. After a brutal initial acceleration, the crew settles into routines. Leigh plants the algae as Earth disappears from the ship's display screen. All three experience fever, depression, and physical illness as the home planet fades, symptoms psychologists theorize represent a biological response to planetary erasure.

The algae exhibit unexpected hypergrowth, each harvest maturing faster than the last. Tyler cuts his arm deeply while cleaning his laptop, and Leigh and K cauterize the wound with a microwave antenna. The crisis bonds them; their biological rhythms converge until sleep patterns, pulse, and metabolic rates align. The crew passes Mars, Jupiter, and Saturn as communication degrades into hours-long delays. Uria tells Leigh that her daughter Maria is pregnant; Leigh realizes Uria will miss the birth.

As Nereus crosses the heliopause, the boundary where the sun's influence ends, and enters interstellar space, the ship shudders and everything goes dark. The crew wakes floating in a dust-covered cabin with all secondary systems dead and all digital records erased. K's manual star readings return impossible results: constellations corresponding to positions from more than two billion years in the past. The crew deteriorates rapidly. Their skin softens, their strength fails, and Tyler can barely walk. The algae, however, continues its explosive growth, the Endeavour genes now fully activated. The three lie side by side on the floor. Tyler asks what will happen when they die. Leigh tells him the ship will continue for millions of years, the algae growing through everything, linking them into a single organism.

The novel shifts to third person, following Helena 13 years after the mission's public declaration as a failure. Living in Jakarta with her husband Jack and two sons, Helena has spent over a decade pursuing a lawsuit against Cable International (CI), the corporate successor to ICORS, for transparency about the crew's fate. She does not remember Geert's violence as severe, and she notes how much Leigh resembled their father in temperament and rituals of control. A letter arrives from Maria, Uria's daughter, revealing that Uria directed the mission and died of brain cancer shortly afterward. Maria identifies a post-mission recovery site: Ascension Island, a remote volcanic British territory in the mid-Atlantic.

Helena and Maria fly to Ascension. On Green Mountain, a peak deliberately terraformed with global seedlings following a suggestion by Charles Darwin, they discover a stone cottage stocked with provisions and marine microbiology texts. Helena recognizes it as the house prepared for the crew's return. That night on Long Beach, she watches giant green turtles, the species Dr. Allen had reported as failing in their migrations, emerge from the sea to nest, their ancient cycle continuing.

In a final section, the narrative returns to Leigh aboard Nereus. The crew has somehow, inexplicably, returned to Earth orbit, but the planet below is entirely blue, a drowned globe with no visible continents. They enter the re-entry capsule and endure a catastrophic descent. Leigh regains consciousness alone, rocking on ocean swells. Tyler and K are dead, algae threading through their bodies. She strips off her suit, opens the hatch, and dives into the water. Her body begins to dissolve, leaving a phosphorescent trail, but the ocean teems with life. In her final moments, Leigh expresses gratitude at being part of this transformation: not ending but beginning again.