On a red-sand world that will one day be called Mars, there are the Three Lands. The Land Above is a vast desert full of thirst and violence and deadly creatures, where nomadic tribes eke out a bare existence. The Great City of Geb sits in a vast sinkhole, where King Tuon rules; other cities likewise rest in deep valleys carved by the subterranean waters which rush beneath them. Then there is the Land Below, a labyrinth of caverns and tunnels where the sunken rivers run and the people never see the sun or the two moons. But King Tuon is old and will soon return to his ancestors, and all his heirs are dead...or are they?