In a vast cavern filled with thousands of Fremen preparing to leave the threatened sietch, Jessica waits beside Stilgar for the rite that will test whether she can become the tribe’s Reverend Mother. Jessica worries about the danger to herself and to her unborn daughter, but believes she must proceed quickly to secure her and Paul’s place among the Fremen. Paul arrives with Jamis’s sons as escorts and learns that Jessica has already agreed to the ordeal.

Chani arrives in mourning for Liet-Kynes, followed by the ancient Reverend Mother Ramallo. Stilgar announces that the tribe must go south and that Ramallo cannot survive another migration, so Jessica will attempt the transformation. To protect the tribe if Jessica fails, Ramallo consecrates Chani as Sayyadina, placing Chani in a supporting ritual role.

The watermasters bring forward a skin of the Water of Life, a dangerous substance from a destroyed maker. Chani offers it to Jessica, who recognizes it as poison but cannot withdraw. After Chani forces a larger drink into Jessica’s mouth, Jessica’s Bene Gesserit-trained awareness suspends her sense of time, identifies the poison’s molecular structure, and alters it within her body. Chani then uses the changed moisture from Jessica as the catalyst to transform the rest of the water so the tribe may drink safely.

Jessica’s consciousness joins with Reverend Mother Ramallo’s, and Ramallo realizes too late that Jessica is pregnant. Jessica must calm the terrified awareness of her unborn daughter, who has been awakened by the ordeal. As Ramallo dies, Ramallo pours her memories and the memories of earlier Fremen Reverend Mothers into Jessica, making Jessica a true Reverend Mother while burdening her daughter with premature ancestral awareness.

Through Ramallo’s memories, Jessica sees the long suffering and migrations of the Fremen, the ancient roots of their culture, and the origin of the Water of Life as the exhalation of a drowned sandworm. Jessica completes the rite by blessing the transformed water and honoring Ramallo’s death. Paul asks whether the water is safe; Jessica tells Paul it has been changed, and Stilgar concludes that Jessica cannot be false.

Paul drinks the transformed water and feels it intensify his prescient powers. Chani leads Paul away to a private room, frightened because the shared water lets her sense the force of his visions and glimpse their future child. As Paul sees the Imperium, Feyd-Rautha, the Sardaukar, the Guild, the Bene Gesserit, and the Fremen jihad converging, Paul also sees a brief hidden period of peace with Chani between storms of violence. Chani accepts the vision, comforts Paul, and promises to stay with him.