Paul and Jessica awake outside their stilltent and set out. A worm is summoned to the thumper Paul has placed, and they inadvertently set off drum sand and have to run to safety in a basin that is clearly man-made, full of plants. Paul and Jessica listen carefully for signs of life and see only a mouse. Despite their attention, the Fremen sneak up on the Atreides, revealing that they can surpass both mentat awareness and Bene Gesserit training.
Liet Kynes, semi delirious and without a stillsuit, is wandering the desert. He chooses not to dig himself under the sand for heat protection because he smells the explosive potential of what he calls the “pre-spice mass”. Though he clearly knows Arrakis better than any he perishes alone in the sand. During his dying moments “a profound clarity filled Kynes’ mind. He saw quite suddenly a potential for Arrakis that his father had never seen. The possibilities along that different path flooded through him.
“No more terrible disaster could befall your people than for them to fall into the hands of a Hero,” his father said.”
Paul and Jessica are recognized by Stilgar, who attended a ducal council and left with Duncan Idaho. The Fremen have been primed to see value in keeping them alive. They see Jessica’s strength and call her a weirding woman, and Stilgar promises his countenance for both in exchange for learning her fighting ways. After their scuffle, Paul finally meets Chani, the girl from his dreams. She gives him food with a strong concentration of spice. Paul, stirred up in prescient visions by it, sees many possible futures surrounding this cave, most hinting at violence, and many ending in his gory death.
Stilgar confirms a suspicion about ecological adaptation, saying “we bribe the Guild with a monstrous payment in spice to keep our skies clear of satellites and such that none may spy what we do to the face of Arrakis.”
He in turn probes her for signs of being the Bene Gesserit from their legends. Jessica leads a prayer with the correct call and response, and awes the Fremen, who welcome her as a future Sayyadina Reverend Mother.
In the climax of the section, the man who Paul bested, Jamis, challenges Jessica in single combat. Since Paul has been tested with a gom jabbar, everyone-- barring Chani, views him as a man, and he takes on Jamis in combat.
Paul wins, despite, or perhaps because of what the Fremen view as unusual and unnerving behaviour. The Fremen baptise him with a private name, dubbing him Usul. He is permitted to choose a public name, and asking what they call the Mouse, christens himself “Muad’dib”.