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.
Tula worries about people accepting her despite her family name; Valya struggles with taking the Sisterhood vow.
Following 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.