Jihae as Mother Kasha.HBOThe series premiere of "Dune: Prophecy," which aired Sunday, ended with a shocking twist.The HBO show is a prequel series set within the universe of Denis Villeneuve's "Dune" movies.The star at the center of the twist spoke to BI about filming her character's big scene.Warning: Major spoilers ahead for "Dune: Prophecy" season 1, episode 1.A pair of shocking deaths close out the first episode of "Dune: Prophecy," the new HBO series that serves as a prequel to Denis Villeneuve's "Dune" movies.The show, set 10,000 years before the birth of Paul Atreides (Timothee Chalamet's character in the films, who was first played by Kyle MacLachlan in David Lynch's original 1984 version of "Dune"), centers on the origins of the Bene Gesserit.The group that would become the Bene Gesserit of the "Dune" films was originally a powerful, mysterious sisterhood, headed by Valya Harkonnen (Emily Watson in the present day, and Jessica Barden in flashbacks).