As Dune begins, a longstanding feud exists between the decadent House Harkonnen of Giedi Prime and the honorable House Atreides of Caladan. The Baron Vladimir Harkonnen's intent to exterminate the Atreides line seems close to fruition as Duke Leto Atreides is lured to the desert planet Arrakis on the pretext of taking over the valuable melange operation there. The Baron has an agent in the Atreides household: Leto's own physician, the trusted Suk doctor Wellington Yueh. Though Suk Imperial Conditioning supposedly makes the subject incapable of inflicting harm, the Baron's twisted Mentat Piter De Vries notes:
| “ | It's assumed that ultimate conditioning cannot be removed without killing the subject. However, as someone once observed, given the right lever you can move a planet. We found the lever that moved the doctor. | ” |
The Baron has taken Yueh's wife Wanna prisoner, threatening her with torture and death unless Yueh complies with his demands. Harkonnen also distracts Leto's Mentat Thufir Hawat from discovering Yueh by guiding Hawat toward another suspect: Leto's Bene Gesserit concubine Lady Jessica. With Jessica herself eliminating suspects though her Bene Gesserit skills of observation and Truthsay, Hawat notes that testing Yueh in this way would be "an empty gesture ... He's conditioned by the High College. That I know for certain." Jessica also notes her knowledge that " wife was a Bene Gesserit slain by the Harkonnens ... Haven't you heard the hate in his voice when he speaks the Harkonnen name?"
The Atreides are soon attacked by Harkonnen forces, and Yueh follows orders and disables the protective shields around the Atreides palace on Arrakis. Also as instructed, Yueh takes Leto prisoner; however, suspecting that the Baron has already killed Wanna, Yueh provides the captive Leto with a fake tooth filled with poisonous gas as a means to kill the Baron (though Leto would die as well).
Yueh discovers that Wanna is indeed dead moments before De Vries kills him, and Leto's poison-gas tooth only kills Leto and De Vries. Leto's son Paul Atreides flees into the desert with his mother, Jessica, aided by survival kits left for them by Yueh. Both are presumed dead, but actually ally themselves with a community of the planet's native Fremen.
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