The Maestro by Tim Wynne-Jones

A Grand piano dangling from a helicopter over the desolate Burl Crow, on the run from his father, it offers a glimps of something rich and strange, a sign of a world beyond his own.

Burl finds himself following the piano's trajectory until, cold, wet and starving, he emerges from the bush onto an isolated lake to hear music -- piano music, unlike any he's ever heard.

It's here he meets Nathaniel Orlando Gow, the Maestro, standing on the deck of a remote cabin, conducting as if he were surrounded by an orchestra rather than a forest and lake. In just one day his eccentric genius changes Burl's life forever -- opening him up to a world her never imagined, one he will fight to keep, even if it means telling the biggest lie of his life.
 
- Goodreads Summary