The Face of Apollo — Fred Saberhagen

Ancient Greece has many heroes. Young Jeremy Redthorn, seemingly doomed to virtual slavery as a farm laborer, doesn't think of himself as one. But when he risks his life for a beautiful, wounded stranger, he soon finds himself on a perilous mission. What he doesn't realize is that the mask he must deliver can confer upon its wearer the powers of a god. And, unfortunately for Jeremy, that god wants it back.