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.

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