Lords of the Triple Moons — Ardath Mayhar

The Old Lords of Rehannoth have been overthrown by rebel leaders who use the powers generated by the great machines to maintain their brutal rule. Only the two surviving children of the Lords, Johab and Ellora, can restore the balance and free their people. But first they must free themselves from captivity--and find the Chasm of Genlith! Part of the series, Tales of the Triple Moons.