Heretics of Dune (1984) is the fifth book in Frank Herbert’s classic science fiction series, the Dune Chronicles. Set 1,500 years after Leto II’s death, the novel centers on the Bene Gesserit’s fight against two threats that seek to destroy them: the Tleilaxu with their formidable genetic technology, and the Honored Matres, a vengeful force with a carnal talent for subjugation. With the leadership of Reverend Mother Darwi Odrade and retired Supreme Bashar Miles Teg, the Bene Gesserit place their hopes on two youths, the ghola Duncan Idaho, and Sheeana, the girl from Rakis (once Arrakis) who can control the giant sandworms. The novel addresses themes of Change and Resistance to the Status Quo, The Critique of Religious Corruption, and Love and Empathy as Vital Human Traits.

This guide refers to the 2019 Ace/Penguin Publishing Group Kindle edition. 

Plot Summary

God Emperor Leto II has been dead for 1,500 years, but the memory of the “Tyrant” still has a hold on the universe. The Tleilaxu have synthesized melange in their axolotl tanks, and the Ixians have invented navigation machines. Both innovations break the monopolies on spice and space travel and alter the power dynamics of the Old Imperium. Adding to the disruption are the populations returning from the Scattering, the exodus catalyzed by Leto’s death, and his Golden Path to save humanity. Among the Lost Ones are the mysterious Honored Matres, a vengeful force of women who use sex to subjugate men.

Sensing these threats to their authority and survival, the Bene Gesserit devise a ghola project. A ghola is an artificially created human, replicated from a dead individual in axolotl tanks from as little as one cell from its original being. They raise a young Duncan Idaho ghola, supplied to them by the Tleilaxu, with the future intention of mating him with Sheeana Brugh, a girl from Rakis (formerly Arrakis) who can control the worms. Reverend Mother Schwangyu supervises the project but objects to the program. She fears the Tleilaxu have tampered with the ghola, or worse, the Bene Gesserit may introduce another Kwisatz Haderach or Tyrant they can’t control. Reverend Mother Superior Taraza, the leader of the Bene Gesserit, insists on continuing the project despite 11 previous failures. Taraza recruits Reverend Mother Lucilla to imprint the twelfth Duncan ghola and secure his loyalties to the Bene Gesserit. Taraza also assigns Miles Teg, the retired Supreme Bashar, to take charge of Duncan’s training and protection. Teg is a direct descendant of the Atreides and his resemblance to Duke Leto I ensures that the ghola’s original memories can be awakened when he comes of age.

The novel’s setting alternates between Duncan's training on the planet Gammu (formerly Giedi Prime) and the veneration of Sheeana on Rakis. Sheeana is a Rakian native who can communicate with the giant sandworms and ride them. The priests of the Divided God regard the worms as incarnations of Leto and worship Sheeana as a child of God. Taraza instructs Reverend Mother Darwi Odrade, Miles Teg’s daughter, to oversee the girl’s training as a Bene Gesserit. During Sheeana’s demonstration in the desert, the worm takes Odrade to the ancient Fremen dwelling, Sietch Tabr. There, Odrade discovers Leto’s hidden hoard of spice and a message from Leto scrawled on the walls. He warns her that the Bene Gesserit has become stagnant and risks falling into obscurity. He impels Odrade to challenge the Sisterhood’s dogmatism and align herself with a noble cause. 

Taraza prompts Odrade to lure the leader of the Tleilaxu, Master Tylwyth Waff, into an alliance to gain information on the Honored Matres and discover what alterations the Tleilaxu may have made on the Duncan ghola. Odrade feigns adherence to the Tleilaxu’s secret religion and warns Waff that the Honored Matres mean to destroy them both. Odrade goes against Taraza’s orders and offers herself and other Bene Gesserit from the Atreides line to serve the Tleilaxu as breeding mothers in exchange for knowledge about their axolotl tanks. She also offers the Bene Gesserit as missionaries to spread the Tleilaxu’s religion. 

The Tleilaxu, who also have a cursory alliance with the Honored Matres, assist in their attack on Gammu to kill Duncan. The Tleilaxu’s new Face Dancers can absorb memories and replicate a person’s physical features. Teg detects their deception and leads Duncan and Lucilla to safety. They shelter in an ancient Harkonnen no-globe where Duncan continues his training. Teg prevents Lucilla from imprinting the ghola and awakens Duncan’s original memories. After months of hiding, Duncan and Lucilla escape with the help of the current Supreme Bashar, Birzmali. The Honored Matres capture Teg and torture him with a T-probe. The agony of the interrogation triggers Teg’s latent Atreides genes. He develops incredible speed and a second vision that enables him to anticipate actions and detect danger. Teg effortlessly obliterates his captors and rallies a group of former soldiers. They help him capture an Ixian no-ship which he locates with his new vision. 

Meanwhile, Duncan, Lucilla, and Birzmali disguise themselves as the enemy and travel to a safe house. Duncan travels separately and is captured by the Honored Matres. When Lucilla and Birzmali reach the safe house, they discover that an Honored Matre named Murbella has taken control and holds Duncan captive. Murbella mistakes Lucilla and Birzmali for an Honored Matre and her client. She allows them to watch her sexual subjugation of Duncan and locks them in a room with an observation window. During the seduction, Duncan gains the memories of all the Duncan Idaho gholas before him. He remembers each death and rebirth and recalls a hazy image of axolotl tanks as metal containers with a network of tubes attached to a giant mound of female flesh. The flood of memories awakens Duncan to the Tleilaxu’s hidden conditioning, and he discovers that he possesses the Honored Matres’ sexual prowess. He resists Murbella’s techniques and counter-seduces her to submission. Lucilla, Birzmali, and Duncan reunite with Teg in his no-ship. They take Murbella as a prisoner and head to Rakis. 

Taraza travels to Rakis to meet Sheeana and confront Odrade for acting independently. Odrade informs her that she has deduced the Tleilaxu’s hidden agenda to endow Duncan with the Honored Matres’ sexual power and have him use it against the Bene Gesserit. Taraza believes Duncan is a liability and must be killed. Odrade, on the other hand, empathizes with the ghola and sees no nobility in making him suffer.

The Honored Matres attack the planet Rakis in search of Duncan. Taraza is wounded and transfers her memories to Odrade before dying. Odrade takes over as the temporary Mother Superior and escapes on a sandworm with Sheeana. Teg picks them up in the desert and transfers the worm to the no-ship’s hold. He tells Odrade to take the ship, Duncan, and the others to Chapter House, the Bene Gesserit’s secret planet. He and his men remain on Rakis as a diversion. Teg’s second vision shows him Taraza’s complete plan, which Odrade learns when she reviews Taraza’s memories after the battle. Taraza had leaked information about Duncan’s conditioning to the Honored Matres to stir them into a bloodlust against Duncan. Teg sacrifices his life to maintain the illusion that Duncan is with him on Rakis, and the Honored Matres destroy the entire planet. Waff and his Face Dancers do not survive. Taraza’s design was to have Rakis and almost all the sandworms obliterated to release humanity from Leto’s hold. The remaining worms will eventually multiply in Chapter House, but Odrade believes humanity will have evolved by then and never submit to the same influences as before. 

For his protection, Duncan confines himself inside the grounded no-ship. Unlike the others, he does not possess the Siona gene that makes him invisible to prescient forces. Duncan refuses to be a breeding stud for the Bene Gesserit, but Murbella is pregnant with his child. Odrade tells him she wishes him to live the life he chooses because her father and her Atreides ancestors loved him. Odrade glances in the ship’s hold and regards the worm as evidence of noble purpose.