Quest for the sun - V M Jones

Adam Equinox has at last discovered his true identity. But then he uncovers a secret in the final page of Queen Zaronel's diary: there was not one baby prince, but two. Zephyr, Prince of the Wind... and Zenith, Prince of the Sun, a twin four times Zephyr's own age. Adam's search for Zenith in Karazan takes him over the Plains of the Dead to the savage nomadic gladiators, who train him to battle the creatures of computer-generated darkness. The chance discovery of the missing half of the Signet of Sovereignty
at last reveals Zenith's secret. Can the brothers be reunited and crowned together as the gong strikes noon on the day of the Equinox? Or is it too late?