Phaeton and the Chariot of the Sun — Michael Cadnum

A child of the sun seeks his father -- and risks destruction for the thrill of speed

In the grazing fields outside the village, a griffin swoops from the sky to attack a lamb. To save the innocent creature, a boy called Phaeton hurls rocks at the assailant, taunting it to come after him instead. As the mythical beast charges, Phaeton turns and runs. The griffin is quick, but it cannot catch Phaeton. He is the fastest boy in the world, and he believes there is nothing he cannot outrun.
 
Phaeton is a child of Apollo, god of the sun. When he learns the nature of his birth, this proud young man embarks on an epic journey to challenge his father and claim his birthright. But even though his heritage is divine, Phaeton is only human. When he comes face-to-face with the might of the gods, he will learn that mortals are not meant to soar so high.