Chapterhouse Dune is a science fiction novel by Frank Herbert, last in his series of six Dune novels. Published in 1985, it is also known variously as Chapterhouse: Dune, Chapter House Dune and Chapter House: Dune.
The Bene Gesserit still find themselves questioning the Golden Path of humanity set by the the God Emperor Leto II. Now they must survive the Honored Matres, whose reckless conquest of the Old Empire threatens Bene Gesserit survival. The Sisters must reassess their timeless methods: does ultimate survival go beyond calculated manipulation? Is there greater purpose to life than consolidating power?
The Honored Matres conquest destroyed the Bene Tleilax, who falsely assumed that their control of spice production guaranteed their protection. The Matres, we come to see, are surprisingly impulsive in their use of violence. A single Tleilaxu Master remains, albeit in Bene Gesserit captivity. He yields a secret of the Tleilaxu: ghola production. The technology compromises Bene Gesserit ethics; the Tleilaxu method requires a human womb — turning women into "tanks" fit for ghola production. The first ghola produced is that of Miles Teg, the great military commander introduced in Heretics of Dune.
The Bene Gesserit have three important prisoners on Chapterhouse, held in a no-ship: Scytale, Duncan Idaho and Murbella (the Matre introduced in Heretics). The Bene Gesserit considers them valuable keys to the present predicament. This mode of thinking — that people are tools fit for a task — makes the prisoners uncooperative, despite the shared threat of the Matres.
The Bene Gesserit intend to wring more secrets of the Tleilaxu from Scytale; namely, how to create spice from the axlotl tanks. Scytale bitterly regrets supplying the Bene Gesserit with ghola technology, but he must barter with them; he is their prisoner. Within Scytale's chest is a nullentropy tube, containing the cells of all Tleilaxu masters and various figures of the last few millennia, including Paul Atreides himself. Capable of recreating the Bene Tleilax, he retains his sense of destiny. Additionally, Scytale also wields the mind-controlling whistling language imprinted in all gholas; what ends could Duncan Idaho achieve for Scytale?
Duncan Idaho and Murbella are living together. The bond created by their mutual imprinting in Heretics has made them somewhat reluctant lovers. The Bene Gesserit have accepted Murbella as a novice and are training her to be a Sister, despite their belief that she intends to steal their secrets and escape back to the Honored Matres.
The Bene Gesserit wonder about Idaho's capabilities and potential; they suspect he remembers more than this ghola existence because they see signs of his being a Mentat, a talent not taught to him. They also wonder why Leto II consistently resurrected Duncan; was it his genetic potential? Indeed, he remembers his serial ghola lives, which mystifies him. His mentat awareness tells him that the Bene Tleilax could not have accomplished this, implying that his awareness is linked beyond genetics.
Lucilla seeks refuge with an underground group whom she knows will be sympathetic to the Bene Gesserit: Jews. Long ago, Jews went underground to escape the repeated pogroms against them. They continued to practice their religion in secret, under cover as "religious revivalists," to conceal their unbroken connection to ancient history. They were so successful that they have survived for 26,000 years while history believed them long since annihilated. The Bene Gesserit — with their memories of the past — were not deceived, and have developed a clandestine relationship with the Jews.
The Rabbi, trapped in the web of mutual obligation, gives Lucilla temporary sanctuary, but in order to save his organization he must deliver Lucilla to the Matres. To Lucilla's shock he reveals Rebecca, a "wild" Reverend Mother who has gained her Other Memories without Bene Gesserit training. Lucilla shares minds with Rebecca, who promises to take the memories of Lampadas safely back to the Sisterhood. Lucilla is then "betrayed" to the Honored Matres.
Back on Chapterhouse, Odrade's plans are reaching fruition. She confronts Duncan Idaho and forces him to admit that he is a Mentat, proving he retains memories of many ghola lives. To some degree this is a relief to Duncan, as he no longer has to disguise his abilities, but he realizes this makes his position still more precarious.
Lucilla is taken before the Great Honored Matre Dama, and to her surprise she is not killed outright. A game of words begins, and the Matre tries to persuade her to join the Honored Matres, preserving her life in exchange for Bene Gesserit secrets. It becomes known that the Matres dearly want to learn to modify their biochemistry as the Bene Gesserit do. It is speculated that the Matres were driven from The Scattering by an enemy who used biological weapons.
Meanwhile, Murbella collapses under the pressure of Bene Gesserit training and pregnancy, giving in to "word weapons" that the Bene Gesserit planted to undermine her earlier Honored Matre identity. Murbella realizes that she really admires and wants to be Bene Gesserit, and sees her former Matres as ignorant children. The words of her initiation are repeated with an emphasis not in the original.
Dortujla, the head of a Sisterhood keep on Buzzell, arrives on Chapterhouse reporting that Handlers and their half-man/half-cat enslaved Futars have offered alliance, though Dortujla's Mentat analysis suggests they intend dominance. She speculates that if the Handlers found Buzzell then Matres may too; smugglers would have sold their information indiscriminately. Why have the Honored Matres not already attacked? Odrade sees an opportunity and orders Dortujla to return to Buzzell with the Sisterhood's offer of surrender. Dortujla is to set up a meeting at Junction — the old Spacing Guild complex — which the Matres control. Unbeknownst to them, Miles Teg has intimate experience with Junction from his human life.
Lucilla's word battles continue for weeks. When she reveals to Dama that although the Bene Gesserit know how to manipulate and control the populace, they practice and believe in democracy, Dama's desire to destroy the Sisterhood is redoubled; the Bene Gesserit teach dangerous knowledge and believe in ridiculous ideas like democracy! Dama kills Lucilla.
Odrade decides that the task of awakening Teg's human memory is best suited to Duncan Idaho, and so he and Murbella take over Teg's training. It is a job that Duncan excels at, but he is not satisfied with the traditional way of awakening a ghola, remembering the pain he went through to release his own memories.
Odrade and Tamalane tour Chapterhouse and visit Sheeana to consider promotion. Arriving at the inland sea of Chapterhouse, Odrade is dismayed to see how small it has become. As she swims, she accepts the ruthlessness of some decisions, and returns to the shore with the decision to accelerate the terraforming by removing the last sea on the planet.
Arriving at Desert Watch station, Odrade confronts Sheeana as a test of her suitability for promotion. But Odrade is undermined by her lingering affection for Sheeana and so does not force the full truth out of her, but discovers that Duncan and Sheeana have been allied together for some time and have exchanged much information. Sheeana does not reveal that they have been considering the option of reawakening Teg's memory through Imprinting, nor does Odrade discover that Sheeana has the keys to Duncan's no-ship prison.
While Odrade is away, Bellonda (a chief advisor to Odrade) decides to get rid of Duncan Idaho, whom she believes is too dangerous. However, she underestimates Duncan's capabilities; when she confronts him he protects himself with Teg, since Teg would never serve them after witnessing the murder of his teacher and friend. With his centuries of awareness — his serial lives — Duncan manipulates Bellonda by revealing his genius as a Mentat. He chides the Sisterhood by focusing on things that they refuse to face, arguing that their emergency plan of Scattering is flawed. Nobody sent to the Scattering has ever returned; therefore they are being trapped. Bellonda leaves, realizing not only that Duncan is too useful to kill, but also that Odrade probably manipulated her into this precise situation. She releases the blocks on Duncan's information flow, giving him full access to the data on the no-ship's computers. "If you have a tool, use it properly," she admits to herself.
Odrade's molding of Scytale continues apace. She points out to him that his dream of Scytale's great revival is fatally flawed, because the Tleilaxu who scattered are no longer true to his beliefs and indeed serve the Matres. Scytale is amazed and terrified when Sheeana arrives with a baby sandworm. The Bene Gesserit now have their long term supply of spice, destroying Scytale's main bargaining card.
At Duncan's suggestion, Teg is awakened by Sheeana using imprinting techniques. Teg's mother had conditioned in him a resistance to imprinting; under Sheeana's sensual assault, his old conditioning is triggered and his memories are awakened. In his awakening he cannot help but reveal the new physical abilities given to him by the T-Probe, the device used by the Honored Matres to torture him in Heretics. Odrade frees and appoints him again as Bashar of the military forces of the Sisterhood for the assault on the Honored Matres.
Finally it is decided that Murbella is ready to become a Reverend Mother. Odrade relaxes the strictures, and for the first time ever, a man — Duncan — is allowed to watch a spice ceremony. Duncan is filled with trepidation, first because he fears Murbella will not survive the ritual, and second because he wonders whether she will still love him after going through such a life changing experience. Odrade watches with equal trepidation because Murbella is vital to her plan to deal with the Honored Matres and to reform the Sisterhood. Odrade believes that the Bene Gesserit made a mistake in fearing emotion, and that in order to evolve, the Bene Gesserit must learn to accept emotions. Murbella, Odrade is pleased to find, takes and survives the hard path to becoming a Reverend Mother.
Murbella goes through a manic phase after becoming a Reverend Mother, and her feelings for Duncan are not the same — a fact that worries Odrade as much as Duncan. Whether it is a temporary effect of the experience or a permanent one is unknown.
Odrade goes to meet the Great Honored Matre with Dortujla and Tamalane. To Odrade's surprise Dama seems cooperative; Odrade wonders whether she was wise to have prearranged the attack. After a while she realizes that Dama intends no reasonable negotiation.
Under cover of Odrade's diplomacy, the Bene Gesserit forces under Teg attack Gammu with tremendous force. Teg uses his secret ability to see no-ships to secure control of the system. Survivors of the attack flee to Junction, and Teg follows them there and carries all with him. Victory for the Bene Gesserit seems inevitable. In the midst of this battle, the Jews (including Rebecca with her precious memories) take refuge with the Bene Gesserit fleet.
Logno — chief advisor to Dama — assassinates Dama with poison and assumes control of the Honored Matres. Her first act surprises Odrade greatly; she surrenders to Odrade. Teg arrives, and reports come in. Too late Odrade and Teg realize they have fallen into a trap, and the Honored Matres use a mysterious weapon hinted at throughout the book to turn defeat into victory. Murbella saves as much of the Bene Gesserit force as she can and they begin to withdraw to Chapterhouse.
Odrade, however, had planned for the possible failure of the Bene Gesserit attack and left Murbella instructions for a last desperate gamble. Murbella pilots a small craft down to the surface, announcing herself as an Honored Matre who, in the confusion, has managed to escape the Bene Gesserit with all their secrets. She arrives on the planet and immediately announces her intentions by killing an overeager Honored Matre with a blinding speed enhanced by Bene Gesserit training that makes her faster than any Honored Matre before her.
Murbella is taken to the Great Honored Matre and immediately declares herself hostile. Unable to control her anger, Logno attacks but is disposed of by Murbella, who becomes Great Honored Matre by having killed her predecessor. Awed by her physical prowess, the remaining Honored Matres are forced to accept her as their new leader. Odrade is also killed in the melee and Murbella Shares with her, thereby also becoming Reverend Mother Superior.
Murbella's ascension to the leadership of the Honored Matres and the Bene Gesserit is not accepted as victory by all the Bene Gesserit. Some feel that she will suborn the spirit of the Bene Gesserit and many worry that her plan of merging the two orders is doomed to failure. Some then decide to flee Chapterhouse, notably Sheeana, who has a vision of her own. They ask Duncan if he wishes to join them, and upon his agreement escape in the giant no-ship, with Scytale, Teg and the Jews from Gammu still aboard. Murbella recognizes their plan at the last minute, but is powerless to stop them, realizing at the same time that Duncan's departure solves many problems for her. Watching this escape with interest are Daniel and Marty, a mysterious pair of observers who by all indications are independent Face Dancers.
The story ends on a cliffhanger with several questions left unanswered regarding the merging of the Honored Matres and Bene Gesserit, the fates of those on the escaped no-ship (including the role of Scytale, the development of Idaho and Teg, and the role of the Jews), the identity of the god-like characters in the book's final chapter and the ultimate mystery of what chased the Honored Matres back into the Old Empire.