The Druid Of Shannara

Description for THE DRUID OF SHANNARA by Terry Brooks:

Quest for the Black Elfstone

In the three hundred years since the death of the Druid Allanon, the mysterious, evil Shadow-en have seized control of the Four Lands. The shade of Allanon summons the four scions of Shannara: Par, Coll, Wren, and Walker Boh. "Io Walker Boh he gives the duty of restoring the lost Druid's Keep, Paranor. For that, Walker Boh needs the black Elfstone, but his search leads him into a trap.

Quickening, the daughter of the ancient King of the Silver River, finds Walker Boh dying after an attack by the Shadowen Rimmcr Dail. She heals Walker Boh and tells him that the Elfstone is in the hands of the Stone King, who seeks to turn all the world to stone. "Io secure the Elfstone they must travel through the Charnal Mountains into the perilous, unknown land beyond. And no one knows what horrible monsters the Stone King has set to guard his citadel.

They form a strange company to undertake the quest: Walker Boll, with only one arm and no longer able to summon his magic; Morgan Leah, whose once-magic sword has been broken; Quickening, who must depend on the men for her defense; and Pe Ell, an assassin who plans eventually to kill her. Thus, the quest for the black Elfstone begins.

This is Books Two of the Heritage Of Shannara.