On the planet Gammu (formerly Giedi Prime), Reverend Mother Schwangyu oversees the secretive ghola project. Duncan Idaho is a 12-year-old ghola, a replicant manufactured by the Tleilaxu from the dead cells of the original Idaho. The Bene Gesserit Sisterhood is known for its breeding programs to produce advantageous political alliances and secure their power in the universe. They hope Duncan can gain influence over Sheeana Brugh, a young girl who can control the giant sandworms worshiped on the planet Rakis (formerly Arrakis or Dune). The Tyrant Leto II has been dead for 1,500 years, but his religious influence persists beyond the Bene Gesserit’s control. 

New rivals called the Honored Matres threaten the Bene Gesserit. They are among the Lost Ones who have returned from the Scattering, a mass exodus following Leto’s death. Because of the failures with 11 previous gholas, Reverend Mother Lucilla is brought in early to imprint Duncan in all forms of love and secure his loyalty to the Bene Gesserit. The Sisterhood typically avoids love but employs emotion as a “safety net” to ensure their success with the 12th ghola. Lucilla does not know the full extent of the project but obeys her orders from the Reverend Mother Superior Taraza, the leader of the Bene Gesserit.