When a half-drowned elf is found floating in the seas of the Blue Divide, an old mystery resurfaces. Thirty years ago, an elven prince led an expedition in search of a legendary magic said to be more powerful than any in the world. Of all those who set out on that ill-fated voyage, not one has ever returned. Until now. The rescued elf carries a map covered with mysterious symbols - and Walker Boh, the last of the Druids, has the skill to decipher them.

Brave explorers led by the last Druid, Walker Boh, traveled across unknown seas in search of an elusive magic. But now it seems that Walker and his team were lured there for sinister, unforeseen purposes. As the crew aboard the airship Jerle Shannara is being attacked by evil forces, the Druid’s protégé, Bek Rowe, and his companions are being pursued by the mysterious Ilse Witch. Meanwhile, Walker is alone, caught in a dark maze beneath the ruined city of Castledown.

Since the death of the Druid Allanon, the Four Lands have changed profoundly, with magic strictly forbidden in the Southland, now under totalitarian rule. Yet Par still has some power of the Wishsong. A message from Allanon arrives: venture to the dread Hadeshorn, along with the other Scions of Shannara. For in the future, all life in the Four Lands will be destroyed. To prevent this terrible fate, Allanon commands Par to recover the long-lost Sword of Shannara, a task that is next to impossible.

Despite denouncing her former life as the dreaded Ilse Witch, Grianne Ohmsford still has bitter enemies within the Third Druid Council. Among the highest ranks lurk those who cannot forget her reign of terror, who covet her seat of power, and who will stop at nothing to see her deposed, or destroyed. Even Grianne's few allies know of the lots against her. But they could never anticipate her sudden, ominous disappearance in the dead of the night without a trace.

In this prequel to The Sword of Shannara, in which many details of the Four Lands' history are revealed, Druids, horrified by the misuse of magic, have eschewed it in favor of science. But Bremen the Druid studies magic, and becomes an outcast on its account. Bremen discovers that an invincible army of trolls are fast conquering all that lay to their south. Before them come the Nazgul-like Skull Bearers, disfigured and transformed Druids who have fallen prey to the dark arts.