Taking place a generation after The Talismans of Shannara, The Voyage of the Jerle Shannara: Ilse Witch opens with the discovery of a body. Only two people understand its significance: Walker Boh, the last of the Druids and a familiar character to Shannara fans, and the Ilse Witch, a beautiful but dark young woman who wields a potent magic. Thus begins the voyage of the Jerle Shannara in a race to uncover the mystery, which of course includes an unusual cast of characters.

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.

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.

Harrowing confrontations with the merciless Ilse Witch and the monstrous Antrax have taken their toll on the intrepid heroes aboard the airship Jerle Shannara. But their darkest adversary now snaps at their heels, in the form of the Morgawr - feeder upon the souls of his enemies and centuries-old sorcerer of unimaginable might with a fleet of airships and a crew of walking dead men at his command. The Morgawr’s goal is twofold: Find and control the fabled ancient books of magic, and destroy the dark disciple who betrayed him - the Ilse Witch.

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.