From "Manual of Muad'Dib" by the Princess Irulan

Something in the position of the pad? she wondered.
But Hawat had been over this room, doubtless had moved the pad. She looked at the leaf above the pad. The leaf! She brushed a finger along the under surface, along the edge, along the stem. It was there! Her fingers detected the subtle coded dots, scanned them in a single passage:
"Your son and Duke are in immediate danger. A bedroom has been designed to attract your son. The H loaded it with death traps to be discovered, leaving one that may escape detection." Jessica put down the urge to run back to Paul; the full message had to be learned. Her fingers sped over the dots; "I do not know the exact nature of the menace, but it has something to do with a bed. The threat to your Duke involves defection of a trusted companion or lieutenant. The H plan to give you as gift to a minion. To the best of my knowledge, this conservatory is safe. Forgive that I cannot tell more. My sources are few as my Count is not in the pay of the H. In haste, MF."
Jessica thrust the leaf aside, whirled to dash back to Paul. In that instant, the airlock door slammed open. Paul jumped through it, holding something in his right hand, slammed the door behind him. He saw his mother, pushed through the leaves to her, glanced at the fountain, thrust his hand and the thing it clutched under the falling water.
"Paul!" She grabbed his shoulder, staring at the hand. "What is that?"
He spoke casually, but she caught the effort behind the tone: "Hunter-seeker. Caught it in my room and smashed its nose, but I want to be sure. Water should short it out."
"Immerse it!" she commanded.
He obeyed.
Presently, she said: "Withdraw your hand. Leave the thing in the water."
He brought out his hand, shook water from it, staring at the quiescent metal in the fountain. Jessica broke off a plant stem, prodded the deadly sliver.
It was dead.
She dropped the stem into the water, looked at Paul. His eyes studied the room with a searching intensity that she recognized—the B.G. Way .
"This place could conceal anything," he said.
"I've reason to believe it's safe," she said.
"My room was supposed to be safe, too. Hawat said—"
"It was a hunter-seeker," she reminded him "That means someone inside the house to operate it. Seeker control beams have a limited range. The thing could've been spirited in here after Hawat's investigation."
But she thought of the message of the leaf: ". . . defection of a trusted companion or lieutenant." Not Hawat, surely. Oh, surely not Hawat .
"Hawat's men are searching the house right now," he said. "That seeker almost got the old woman who came to wake me."
"The Shadout Mapes," Jessica said, remembering the encounter at the stairs. "A summons from your father to—"
"That can wait," Paul said. "Why do you think this room's safe?"
She pointed to the note, explained about it.
He relaxed slightly.
But Jessica remained inwardly tense, thinking: A hunter-seeker! Merciful Mother! It took all her training to prevent a fit of hysterical trembling.
Paul spoke matter of factly: "It's the Harkonnens, of course. We shall have to destroy them."
A rapping sounded at the airlock door—the code knock of one of Hawat's corps.
"Come in," Paul called.
The door swung wide and a tall man in Atreides uniform with a Hawat insignia on his cap leaned into the room. "There you are, sir," he said. "The housekeeper said you'd be here." He glanced around the room. "We found a cairn in the cellar and caught a man in it. He had a seeker console."
"I'll want to take part in the interrogation," Jessica said.
"Sorry, my Lady. We messed him up catching him. He died."
"Nothing to identify him?" she asked.
"We've found nothing yet, my Lady."
"Was he an Arrakeen native?" Paul asked.
Jessica nodded at the astuteness of the question.
"He has the native look," the man said. "Put into that cairn more'n a month ago, by the look, and left there to await our coming. Stone and mortar where he came through into the cellar were untouched when we inspected the place yesterday. I'll stake my reputation on it."
"No one questions your thoroughness," Jessica said.
"I question it, my Lady. We should've used sonic probes down there."
"I presume that's what you're doing now," Paul said.
"Yes, sir."
"Send word to my father that we'll be delayed."
"At once, sir." He glanced at Jessica. "It's Hawat's order that under such circumstances as these the young master be guarded in a safe place." Again, his eyes swept the room. "What of this place?"
"I've reason to believe it safe," she said. "Both Hawat and I have inspected it."
"Then I'll mount guard outside here, m'Lady, until we've been over the house once more." He bowed, touched his cap to Paul, backed out and swung the door closed behind him.
Paul broke the sudden silence, saying: "Had we better go over the house later ourselves? Your eyes might see things others would miss."
"This wing was the only place I hadn't examined," she said. "I put if off to last because . . ."
"Because Hawat gave it his personal attention," he said.
She darted a quick look at his face, questioning.
"Do you distrust Hawat?" she asked.
"No, but he's getting old . . . he's overworked. We could take some of the load from him."
"That'd only shame him and impair his efficiency," she said. "A stray insect won't be able to wander into this wing after he hears about this. He'll be shamed that . . ."
"We must take our own measures," he said.
"Hawat has served three generations of Atreides with honor," she said. "He deserves every respect and trust we can pay him . . . many times over."
Paul said: "When my father is bothered by something you've done he says 'Bene Gesserit!' like a swear word."
"And what is it about me that bothers your father?"
"When you argue with him."
"You are not your father, Paul."
And Paul thought: It'll worry her, but I must tell her what that Mapes woman said about a traitor among us .
"What're you holding back?" Jessica asked. "This isn't like you, Paul."
He shrugged, recounted the exchange with Mapes.
And Jessica thought of the message of the leaf. She came to sudden decision, showed Paul the leaf, told him its message.
"My father must learn of this at once," he said. "I'll radiograph it in code and get if off."
"No," she said. "You will wait until you can see him alone. As few as possible must learn about it."
"Do you mean we should trust no one?"
"There's another possibility," she said. "This message may have been meant to get to us. The people who gave it to us may believe it's true, but it may be that the only purpose was to get this message to us."
Paul's face remained sturdily somber. "To sow distrust and suspicion in our ranks, to weaken us that way," he said.
"You must tell your father privately and caution him about this aspect of it, " she said.
"I understand."
She turned to the tall reach of filter glass, stared out to the southwest where the sun of Arrakis was sinking—a yellowed ball above the cliffs.
Paul turned with her, said: "I don't think it's Hawat, either. Is it possible it's Yueh?"
"He's not a lieutenant or companion," she said. "And I can assure you he hates the Harkonnens as bitterly as we do."
Paul directed his attention to the cliffs, thinking: And it couldn't be Gurney . . . or Duncan . Could it be one of the sub-lieutenants? Impossible. They're all from families that've been loyal to us for generations—for good reason .
Jessica rubbed her forehead, sensing her own fatigue. So much peril here! She looked out at the filter-yellowed landscape, studying it. Beyond the ducal grounds stretched a high-fenced storage yard—lines of spice silos in it with stilt-legged watchtowers standing around it like so many startled spiders. She could see at least twenty storage yards of silos reaching out to the cliffs of the Shield Wall—silos repeated, stuttering across the basin.
Slowly, the filtered sun buried itself beneath the horizon. Stars leaped out. She saw one bright star so low on the horizon that it twinkled with a clear, precise rhythm—a trembling of light: blink-blink-blink-blink-blink . . .
Paul stirred beside her in the dusky room.
But Jessica concentrated on that single bright star, realizing that it was too low, that it must come from the Shield Wall cliffs.