An epigraph frames Paul Atreides, later known as Muad’Dib, as a figure who must be understood through Arrakis, even though Paul was born on Caladan. In the week before House Atreides leaves Caladan for Arrakis, an aged Bene Gesserit woman visits Lady Jessica and peers in at Paul, hinting that Paul may be the Kwisatz Haderach and warning that Paul will face her gom jabbar the next day.

Paul lies awake amid the upheaval of departure and considers what Paul has learned about Arrakis. The Harkonnens, mortal enemies of House Atreides, have mined the spice melange there for eighty years, and Duke Leto’s apparent gain of Arrakis may actually be dangerous because Leto’s popularity threatens powerful rivals. Paul dreams of a solemn Arrakeen cavern and knows he will remember the dream because some of Paul’s dreams are predictive.

At dawn, Jessica prepares Paul to meet Reverend Mother Gaius Helen Mohiam, the Emperor’s Truthsayer and Jessica’s former Bene Gesserit teacher. Jessica shows fear when Paul asks about the gom jabbar, then brings Paul to Mohiam. Mohiam dismisses Jessica, and Paul notices both Jessica’s fear and Mohiam’s use of the Voice to compel obedience.

Mohiam orders Paul to put his hand into a black box and holds the gom jabbar, a poisoned needle, at Paul’s neck. Mohiam explains that if Paul removes the hand, Paul will die, and that the test distinguishes humans from animals by seeing whether Paul can endure pain rather than obey instinct. Paul recites the Litany against Fear, withstands agonizing nerve-induced pain, and does not withdraw his hand.

After the test ends, Paul’s hand is unharmed, and Mohiam calls Paul a young human, shaken because Paul endured more than expected. Jessica reenters, relieved that Paul lives, while Paul senses that the test has infected him with a terrible purpose. Mohiam explains that the Bene Gesserit test and observe people, preserve human abilities after the Butlerian Jihad, and conduct breeding programs to seek the Kwisatz Haderach, a man who can see into both feminine and masculine ancestral pasts; men who have tried to reach this state through the Truthsayer drug have died.