Long ago the Jinn Lord Al-Marid was sealed beneath the black massif at the centre of the Najd. The sealing split the desert in two: the Light, who keep the sun-facing city in the east, and the Dark, who hold the moon city in the west. Generations later the seal is thinning, the cave beneath it reshapes itself with every descent, and both banners send heroes into the sand — some to hold the seal, some to see what waits under it.