On Wallach IX, young Valya Harkonnen promises Mother Superior Raquella that she’ll protect the Sisterhood by putting one of their own on the Imperial Throne. Thirty years later, Valya faces a threat to her long-awaited plan.

After receiving word about events on Salusa Secundus, Valya brings Theodosia to the Imperial House to help manage the situation. Meanwhile, a reluctant Tula enlists Lila for a vital mission.

Following a tragedy, young Tula worries about being accepted despite her family name, while a skeptical Valya struggles with the decision to take the Sisterhood vow. Years later, Valya receives a message that confirms her suspicions.

As Tula attempts to understand the acolytes’ shared dream, Valya sets her plan in motion to redeem House Harkonnen ahead of the Landsraad.

While Tula tries to keep her secret project from being discovered by the other Sisters, Desmond goes on a warpath to root out insurgents.

Follows two Harkonnen sisters as they combat forces that threaten the future of humankind, and establish the fabled sect that will become known as the Bene Gesserit.