Clifford D. Simak 
Enchanted Pilgrimage [EPUB ebook] 

Their quest was to find the Elders. But hellhounds, witchcraft and harpies barred their way. From the theft of a manuscript in a fusty library an amazing tale develops. From a young man’s obstinate questions emerges an answer of stupendous import. The quest for an elder civilisation becomes a terrifying ordeal. Enchanted Pilgrimage is like no other fantasy novel — a stunning adventure set in an alternative universe where myths still walk the earth.