Two Harkonnen sisters combat forces that threaten the future of humankind and establish the fabled sect that will be known as the Bene Gesserit.
Following a tragedy, young Tula worries about being accepted despite her family name; a skeptical Valya struggles with the decision to take the Sisterhood vow; years later, Valya receives a message that confirms her suspicions.
Tula tries to understand the origins of the nightmare that affects all acolytes of the sisterhood; as Tula attempts to understand the acolytes' shared dream, Valya sets her plan in motion to redeem House Harkonnen ahead of the Landsraad.
As Corrino names a new Bashar, a Sister with deep connections to the Emperor arrives on Salusa Secundus; after receiving a tip, Desmond goes on a warpath to root out the insurgents; Tula tries to keep her secret project from being discovered.
As Tula contends with the reveal of Desmond's true identity, the acolytes uncover a devastating long-held secret about the Sisterhood.