We learn from the introductory biographical note, as well as from Dr. Yueh’s own thoughts, that he is the traitor to the Atreides. Paul is joined by his father, Duke Leto, in the training room. Leto admits that they are walking into a trap set by Baron Harkonnen, but he believes that the Atreides can survive if they keep their eyes open. Leto reveals to Paul that the Harkonnens have been stockpiling melange, the spice drug, and plan to destroy the production of it on Arrakis while also obliterating the Atreides. Destruction of the spice supply would drive the prices of melange so high that the Harkonnens would gain control, while the Atreides shoulder the blame for the high prices. Leto tries to allay Paul’s fears; Leto believes that the Atreides can beat the sneaky baron at his own game.

Soon the Atreides arrive on planet Arrakis. Lady Jessica meets her new servant, Shadout Mapes, who is a Fremen—a native of Arrakis. The native has been sent to test Jessica, and since she is a Bene Gesserit, a member of a special ancient school for women, Jessica passes the test. Jessica correctly identifies a strange knife that Mapes shows her, calling it a maker. Mapes refers to Jessica as “the One.”

Jessica then goes to find Paul but instead finds Dr. Yueh. Paul is sleeping in the next room. Jessica and Yueh discuss Arrakeen politics, particularly the fact that some natives resent their rulers for the extravagant use of water on a planet that has practically no water. Other natives believe that the Atreides bring hope to Arrakis, in contrast to the previous Harkonnen rule. Yueh, who is desperately trying to conceal his traitorous plans from Jessica, who has Bene Gesserit mind abilities, reveals one small truth: his wife, also a Bene Gesserit, was taken and presumably killed by the Harkonnens.

In Paul’s bedroom, a small robotic probe appears from behind the headboard and tries to kill him, but Paul manages to escape. The Atreides troops find a man beneath the palace, where he had been controlling the deadly robotic probe. Meanwhile, Jessica discovers the palace greenhouse, where thousands of plants are given hundreds of gallons of water per day. She also discovers a note from another Bene Gesserit, Lady Fenring, who belatedly warns Jessica about the assassination attempt on Paul. Fenring warns that a traitor is in their midst. Paul runs into the greenhouse, and Jessica tells him of the message.

The duke, rattled by the attempt on his son’s life, attempts to move on with business, assigning Halleck, the war master, to convince the spice miners of Arrakis to continue working for the Atreides.

The duke meets with Paul and Thufir Hawat, the master of assassins. Hawat tries to resign for his failure to protect Paul, but the duke refuses to let him. The duke calls a meeting of all his men. They make several plans: to infiltrate the spice smugglers’ network and win their support; to prepare for the impending Harkonnen trap; to raid in secret the Harkonnen spice reserves on another planet; and to recruit the Fremen as warriors to fight any possible threat. The Atreides also discuss Liet, the mysterious, perhaps godlike leader of the Fremen. While at the meeting, Duncan Idaho returns, along with a Fremen leader, Stilgar. Duncan, the swordmaster, has won Stilgar’s respect, and the duke, with his respectful attitude, also wins Stilgar’s respect. Stilgar offers Duncan a place in his sietch, a protective cave, and with the duke’s blessing, Duncan agrees to join the Fremen. As the meeting breaks up, Paul recalls the Reverend Mother Mohiam’s warning that his father would not be alive for long on Arrakis.

This section of Dune introduces us to Arrakis, the desert world that is the setting for most of the novel. The most important aspect of life on Arrakis is the need for water, and there are signs of this need everywhere. There is the greenhouse, which uses thousands of gallons of water a day to water its plants. The greenhouse is a show of extravagance but also a sign of hope that the landscape of Arrakis can be transformed into a lush paradise. A small cut that Jessica makes on Shadout Mapes stops bleeding almost immediately; such swift clotting is necessary when water is so precious. To show his respect for the duke, Stilgar spits on the table. Stilgar gives up some of his moisture, which is a precious gift. Later in the book there are more examples of the supreme importance of water for the Fremen. Fremen do not use the word blood when referring to an important, limited life force, but instead they use water.

The lack of water is a sign of the planet’s precarious ecology. One of Dune’s themes is mankind’s ability to live within a planet’s ecological system and humanity’s ability to disrupt that system, with either good or ill results. Frank Herbert got his initial idea for Dune after studying a governmental ecological project designed to halt the spread of sand dunes on the Oregon coastline. Examples of humanity altering a natural, ecological process can be found throughout Dune, but the most apparent is the Fremen’s hopes to change Arrakis from a desert planet to a lush, Edenic paradise. Such a transformation sounds ideal. However, even changes made with good intentions can have negative consequences. Herbert is well aware of the ambiguity in ecological preservation—Dune stops short of taking a definitive stance on how humans should interact with their environment.

Another important development in this section is the Fremen’s identification of Jessica as being a Bene Gesserit. We learn that the Bene Gesserit have, some time in the distant past, traveled the galaxy to many worlds, implanting generic myths about themselves that later generations of Bene Gesserit could use to their advantage if they become stranded on an unfamiliar planet. In this case, the Fremen have learned legends of a Bene Gesserit woman who will be the mother of their savior. The legends were originally intended to allow a Bene Gesserit to find help if she needs it and to be accepted by the general population if she found herself on a new planet. In the case of Jessica and the planet Arrakis, as hinted by the quotes from Princess Irulan before each section, the legends will be more accurate than ever before.

The sheer size and complexity of the world Herbert creates is overwhelming. Aside from the number of main characters, the action is set against a large background of intergalactic politics. At the core of the story is the idea that a simple desert planet like Arrakis can play a major role in determining the course of the galactic empire. The importance of Arrakis, however, lies not so much in Paul, but in the planet’s production of melange, the spice drug to which so many people are addicted. The incredible value of the spice drug is the reason the Atreides are so suspicious that the emperor is handing Arrakis over to them. All of the characters, from Duke Leto to Paul to Jessica, know that the Atreides are walking into a trap. While the duke may hope that he can avoid the trap, Jessica and Paul know the truth: the duke will not live much longer. Throughout the novel, there is a tension between fate and Paul’s struggle to guide his own future.