Humanity attempted to avert a looming ecological catastrophe by heavily investing in genetic technology, but those efforts proved futile. Engineered viruses and organisms escaped into nature, decimating edible plants, animals, and a significant portion of the human population. In the aftermath, an oligarchy thrives in fortified cities known as 'citadels,' while the rest of humanity struggles to survive in the desolate world outside. The people are dependent on modified seeds provided by the citadels, but these seeds are designed to yield just a single harvest.
Outside the citadel's walls, survival is a grim endeavor. The modified seeds require a special process for fertility, known only to the citadel's scientists. Among the survivors is Vesper (Raffiella Chapman), a resourceful 13-year-old girl living in a remote house with her father Darius (Richard Brake), who is paralyzed. Darius communicates through a drone resembling a floating robot head, aiding Vesper in her daily life while his physical body remains bedridden. Driven by desperation, she conducts bio-hacking experiments in an abandoned laboratory to cultivate the seeds without needing the citadel's elaborate processes.
A year prior, Vesper's mother left to join a group called The Pilgrims, who roam the wasteland scavenging without revealing their identities. Vesper's uncle, Jonas (Eddie Marsan), oversees a makeshift orphanage nearby, but his intentions are far from altruistic; he exploits the children by extracting their blood to sell to the citadel. Furthermore, Jonas possesses artificial beings known as Jugs (Melanie Gaydos), created merely to serve as laborers.
Desperately needing supplies, Vesper trades her own blood to Jonas, yet she resists his attempts to coerce her into becoming a breeder. When Jonas denies her promised resources, Vesper decides to steal bacteria and seeds from his property to power her generator, which keeps her father alive. A pivotal moment arrives when a citizen ship from the citadel crashes nearby, and Vesper bravely rescues a survivor, Camellia (Rosy McEwen). As Vesper nurses Camellia back to health, she learns that Camellia was also a passenger and that if they can locate another survivor, Elias (Edmund Dehn), they may receive passage to the citadel.
However, when Vesper returns to check for Elias, she is met with tragedy; Jonas has killed him and suspects further survivors. Vesper keeps Camellia's presence a secret, yet through determination, Vesper aspires to establish communication with the citadel to secure Camellia’s safety. In revealing her greenhouse, Vesper shares her experimental work with Camellia, who discloses that Elias is a leading figure in synthetic biology at the citadel and would be very interested in Vesper’s advancements.
In a desperate act of resolve, Vesper sneaks back to Jonas's farm but is caught once more. She cleverly fabricates a story to escape. However, when she later finds the lifeless body of one of Jonas's orphans, a painful realization dawns on her. Upon revealing the death of Elias to Camellia, Vesper witnesses her deep sorrow, uncovering a secret: Camellia is not merely a human survivor but an extraordinarily advanced Jug, designed for complex emotions and human resemblance. The truth of her existence leads to a revelation that Elias, the very maker of Camellia, escaped the citadel due to his controversial work, leading to drastic measures when captured.
Seizing the opportunity, Vesper utilizes the stolen seeds in conjunction with Camellia's genetic composition, unlocking the potential for the seeds to grow without citadel processes. Together, they discover that Elias intended for this innovation to dismantle the citadel's control over food supplies.
The situation turns dire as Jonas discovers Camellia’s secret. In a harrowing confrontation, Vesper and Camellia manage to overpower him. Vesper offers a deal: Jonas can keep the seeds in exchange for leaving them unharmed. However, he betrays them by alerting the citadel about Camellia, leading to Jonas's swift demise at the hands of citadel soldiers.
In the chaos, Darius sacrifices himself, detonating their home’s reactor to buy Vesper and Camellia precious time. Their desperate escape leads to a gripping encounter with citadel soldiers, and in a heart-wrenching decision, Camellia allows herself to be captured, leaving Vesper behind with a message of hope: she possesses the seeds that could change everything.
Overwhelmed with grief, Vesper buries the seeds, convinced their potential is worthless without her loved ones. Yet, when a band of Jonas's children comes across her, Vesper reclaims her purpose. In an inspiring moment, the children join her in a quest to find a tall structure built by The Pilgrims. There, she unearths the seeds one last time and frees them to the wind, embracing the opportunity to revive hope in their ravaged world.
