A few parsecs from the Earth, on the very outskirts of the human Ecumene, the planet Astyre, scorched by a nearby star, revolves. It is impossible to survive on its surface, but this celestial body has long been colonized. The people inhabiting Astira hide in the depths, where they mine a mineral that promises to give immortality to humanity. Nothing foretells a catastrophe, until one day communication with several distant settlements is interrupted. Groups sent to find out the reason for the silence disappear without a trace. What's happening? Bioterrorism? Sabotage? Epidemic? The people of Astir do not yet know that they are faced with a threat the likes of which they have never encountered before.