The film begins with a quote from the Ocean Book of Escape: "… and they ascended into that silence at the very top of the world / where all they could hear was their self." Set in a distant future, Earth is partially occupied by a gentle alien species called the Oieans. Despite their peaceful presence, their increasing numbers stir unrest among humans, leading to conflicts and social tensions. In this harsh world, those accused of serious crimes such as murder, terrorism, or treason may be banished to uninhabited planets as a form of life imprisonment, where they are left entirely alone.
The story primarily follows an aging man, Elias Koteas, who is the sole prisoner on Solitary Penal Planet #384. His days are filled with backbreaking work mining a luminous alien ore, which is then sent higher into orbit. Isolated from any human contact, he struggles to keep his sanity, often reminiscing about his past life on Earth. He spends his free time composing letters to his wife Mona (whose presence lingers in his memories), watching AI-generated sitcoms on his personal AI TV device called V8, and fighting loneliness and despair. His biggest fear is a purple alien gas that drifts toward his colony, which he suspects has sentient properties and worsens negative thoughts.
One day, his life takes an unexpected turn when the gas prompts a diagnosis alert: he is terminally ill. In an act of desperation, he removes his life-monitor implant, a device that keeps him alive but also monitors his health. This decision results in the arrival of a new prisoner, Briana Middleton, who is initially suspected to be sent to kill him. His fears lead him to sneak aboard her habitat ship while she is allegedly asleep and steal her journal. After an initial confrontation, Theodore, as he calls himself, along with another prisoner, Niyya, gradually open up and forge an uneasy alliance, working together in the mines.
As their relationship develops, Theodore invites Niyya to his quarters for dinner, where they share stories of their lives—she recounts coming from City 12 in North America and being raised by Oieans in the Black Sea, while he reveals he was framed for murder. They also exchange the crimes they committed: Theodore confesses he is unsure of his true memories, suspecting he might not recall everything accurately, and Niyya admits she was accused of trying to assassinate the prime minister. During their evening, Theodore even shares an alcohol and medicinal cannabis with her, deepening their connection. He then mentions that his real name might have been Nathan Flanagan, linking him to a military officer who shot Oieans that raised Niyya, whom she considered family.
However, under the influence of the purple alien gas, Niyya’s suspicion grows, and she begins to blame Theodore for the murder of her Oiean family. Her mistrust leads her to hide in an abandoned habitat ship of a third, unnamed prisoner—who had been exiled there earlier and eventually hanged himself—and in her rage, she hits Theodore with a shovel. This triggers him to remember the tragic truth: he was the one who murdered his wife Mona, vividly recalling the moment he stabbed her with a knife. Overcome with grief, Theodore breaks down, crying as Niyya departs in distress.
The derelict habitat ship she leaves behind is covered in horrifying graffiti—images of human bodies in agony and the chilling words, “Filth! They all deserved to die!”—a reflection of the deep, tangled negative thoughts influenced by the gas, now fused with their own subconsciouses. Later, Niyya revisits her journal, written mostly in Oiean script with some English, and finds the name “Nathan Flanagan,” which makes her question her assumptions. As the gas intermittently engulfs her ship, she becomes overwhelmed by negative thoughts that are not entirely her own; overwhelmed with emotion, she cries.
She then returns to Theodore, asking if he believed his name was "Nathan Flanagan" because he read it in her journal. Theodore concedes that was possible, and he proposes an unusual plan: to have her life monitor implant moved to him, so that when he finally succumbs to his injuries, he can be considered dead, freeing her from her work in the mines. In the end, Theodore passes away peacefully. Niyya gently covers his body with a blanket, closes his habitat, and leaves. She then ascends a nearby mountain, where she sits quietly, staring into the distant horizon, contemplating her future and the life she must now forge on her own.
