On Wallach IX, young Valya Harkonnen makes a promise to the Sisterhood. Thirty years later, Valya faces a threat to her long-awaited plan.

While Valya recruits Theodosia to help manage the situation on Salusa Secundus, a reluctant Tula enlists Lila for a vital mission.

Years earlier, Tula worries about being accepted despite her family name, while Valya struggles with taking the Sisterhood vow.

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.

As Tula contends with his true identity, Valya’s maneuvering leads her into an epic confrontation with an increasingly powerful Desmond.