Lu wakes inside a coffin-like capsule with no memory of who he is or how long he has been asleep. He calls out for help and is rescued by Claude, a self-proclaimed five-hundred-year-old archmage who seems to be the only other living person in the world. The planet has been completely reclaimed by nature, with buildings overtaken by vines and trees, leaving behind an eerie, abandoned landscape the two travellers explore.

The boy, who Claude names Lu, searches for other coldsleep pods in the hope of awakening more survivors. Although Lu has no recollection of the past, he ventures through the ruins with Claude, who is often grumpy and prone to sleeping for long stretches. During their journey, Claude sees looming black humanoid shapes at dusk, while Lu perceives only small lights drifting nearby, which Claude calls fireflies. This symbolic gap separates the child, whose name may derive from the French word for firefly, from an immortal companion haunted by the weight of centuries.

In a notable narrative arc, Lu discovers an undisturbed coldsleep pod that contains Bruno, one of the engineers who designed the pods. After Bruno awakens, he communicates in a language Lu does not initially understand, but the boy gradually learns to speak with him. Bruno reveals that he is searching for the pod holding his pregnant wife, adding a new layer of urgency to their travels. The volume concludes with two unresolved cliffhangers, including a flashback sequence showing a young man with Claude’s hairstyle yet Lu’s features, leaving the nature of reality and memory open to interpretation.