The Unknown Quest - The Horns of Elfland, #1

The Unknown Quest is the first book of The Horns of Elfland. It is aimed at readers aged 15+Thousands of years ago, one of Sherath's distant ancestors refused to take on a quest. The task has to be done - it's vitally important - but nobody knows exactly what it is. Their race is dying out, and time is running out; and until Sherath comes into his full powers, he can't do it anyway. They have been waiting three hundred years for the saviour spoken of in an ancient prophecy to lead them on a long journey to adulthood and open the doors for them.
But their saviour, and the key to success, turns out to be a volatile teenager from modern-day Earth. Sherath has hundreds of years of education in how to use the Power he will have as an adult, with little access to it as yet. Farinka, on the other hand, has access to vast amounts of Power, but no training in how to use it, what can and can't be done, and what is dangerous to try!