The Oracle - The Oracle Trilogy (Unabridged‪)‬

In a land without rain, the people turn to the Archon, the god-on-Earth, to end their suffering and, for their sake, the old man must make a terrible sacrifice.
Suddenly Mirany, a young priestess, finds herself thrust unwillingly into a desperate struggle to find the child who will be the new Archon. And the only help that she can find are Oblek, a drunken musician and Seth, a conniving scribe. If she fails, General Argelin and the high priestess Hermia will install a false candidate of their own and so gain absolute power.
Nominated for the Whitbread Children's Book Award.