Elpek was a Senior Dame and Honored Matre of the Hormu during the events of Chapterhouse: Dune.
After the Bene Gesserit's military disaster on Junction, only two hopes remained for the Sisterhood: Murbella and Sheeana.
Sheeana was safe on Chapterhouse, but Murbella decided that, in that critical moment, decisive measures were required, so she went to Junction, where Mother Superior Darwi Odrade was held captive, to play her last card in order to save the Bene Gesserit. When she arrived on Junction, she was received by Elpek, who is described as "An ancient Honored Matre...her red robe stained, some of its decorations gone and a rip down the left shoulder. She was like some dried-up lizard, still poisonous, still with a bite but running on well-used angers, most of her energy gone. Disarrayed hair like the outer skin of a fresh-dug ginger root. There was a demon in her. Murbella saw it peering from orange-flecked eyes".
Elpek recognized Murbella as one of the Rocs, a deadly type of Honored Matre trainee. She tested Murbella, questioning her about her former commander, Hakka. Then, when Murbella told Elpek about her new talents as both Honored Matre and Bene Gesserit, she accepted her as a gift, and took her in presence of the new Great Honored Matre, Logno. Immediately after she was taken in Logno's presence, Murbella declared her hostility towards her, and Logno attacked her, but Murbella's new skills surpassed Logno's ones, and she killed her. During the melee, Darwi Odrade tried to intervene, and Elpek broke her neck. When Murbella realized Odrade was dead, her rage turned unstoppable, as Elpek thought she had done something normal by killing Odrade, however, Elpek didn't realized that Murbella wasn't any longer just an Honored Matre, but also a Bene Gesserit Reverend Mother. Almost instantly, Murbella kicked Elpek's larynx, and Elpek's dead body sprawled across Odrade's one.
Then, Murbella became the Great Honored Matre and Mother Superior of the Bene Gesserit, opening the way for a new Sisterhood she would form, according to Odrade's plans.