In "Dune", Mohiam is the Imperial Truthsayer, and the mentor of Lady Jessica, the Bene Gesserit concubine of Duke Leto Atreides. Mohiam is interested in Jessica's young son Paul Atreides, who is a key figure in the Bene Gesserit breeding program but has also displayed unusual potential. She ultimately loses any influence she may have had over Jessica or Paul, who ally themselves with the native Fremen of Arrakis and depose Padishah Emperor Shaddam IV. In "Dune Messiah", Mohiam joins a conspiracy to remove Paul from power, which fails.