Nobody wants to leave Kour prison, despite the scorching hot climate on planet Sioulann's poles! The city is on the verge of bankruptcy, because its prefect, Juunus, supports a hidden village where ex-prisoners can leads their own life. Then, questor Sirius is stricked down by a strange illness. Is it linked to the Koudriss'axis, the spectacular borealis auroras that could hide a mortal menace? The evacuation of Kour is launched, but the village's residents, proud of their freedom, have fled to the mountains. Among them, young Feli, near the end of her pregancy. Will Chaaas find them in time?