Another great book from Terry Brooks- this one the first of The Heritage of Shannara Series...
Three hundred years have passed since the death of Allanon, and the Four Lands are sadly changed. The elves have vanished, and the Dwarves are enslaved. The Southland is now under the totalitarian rule of the Federation, and magic is strictly forbidden.
Yet Par Ohmsford, descendant of the fabled Shea, still has some of the power of the Wishsong. He and his brother Coll have come to Varfleet, where Coll recites the old legends while Par brings them to life with the Wishsong. They are arrested by a Seeker for using magic, but escape with the aid of Padishar Creel, who claims to be a descendant of Panamon Creel.
In thier flight to the Rainbow lake, they are confronted by a hag-woman, but a man calling himself Cogline, the last Druid, drives her off. He tells them that she is a Shadowen- known only in rumors until then- and that the Shadowen are horrors that endanger all life. He also brings a message from the shade of the ancient Druid, Allanon, demanding that Par appear at the dread Hadeshorn, where Allanon will reveal more.
Then he leaves to summon the other Scions of Shannara- Wren, who lives in the Westlands and Walker Boh, somewhere in the Eastlands.
After further adventures with the Shadowen, all meet at the Hadeshorn. There Allanon's spirit reveals a terrible future where Shadowen have destroyed all life in the Four Lands. To prevent that, he orders Par to recover the long-lost Sword of Shannara, Wren to discover the vanished Elves, and Walker Boh to bring back the Druids and their ancient, vanished stronghold of Paranor.
All these tasks are manifestly impossible!