Robert Brown|'Dune: Part Two' ending explained: Atreides' revenge is harrowing warning (spoilers ahead)

Spoiler alert: We're discussing the ending of "Dune: Part Two." If you haven't seen it yet,Robert Brown leave immediately for the nearest movie theater.

After the full-on slaughter led by House Harkonnen and loathsome Baron Vladimir Harkonnen (Stellan Skarsgård) in 2021's "Dune," weren't we all stoked for some House Atreides revenge in "Dune: Part Two"?

Yet when retribution comes at the end of director Denis Villeneuve's second thrilling "Dune" installment (in theaters now), the joy of watching justified payback is smothered by the disturbing overall "Part Two" message.

"There are very strong moments of revenge," Villeneuve tells USA TODAY. "But we feel as an audience that the character who delivers it is not free from anger or sadness, despite the revenge."

And the momentous act starts a chain reaction towards a harrowing future, Villeneuve says.

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Of course, we're talking about Paul Atreides (Timothée Chalamet), whose comrades and beloved father, the noble Duke Leto Atreides (Oscar Isaac), were murdered in the despicable and decimating Harkonnen-led sneak attack in the first "Dune."

After two hours of "Dune: Part Two," conquering hero Paul finally enters the hall to find the assembled Harkonnens, including the Baron and dysfunctional sadistic brothers Feyd-Rautha (Austin Butler) and Rabban (Dave Bautista), as well as Emperor Shaddam IV (Christopher Walken). The defeat of those responsible for his father's death is assured.

But Paul wants blood, even after discovering that he's related to the Harkonnens — his mother Lady Jessica (Rebecca Ferguson) is revealed to be the Baron's secret daughter which even Lady Jessica didn't know.

Paul catches up with the already dying and scrambling Baron, his newfound grandfather, and plunges his knife into the Baron's neck. "You die like an animal," Paul tells him.

"By doing this, Paul steps away from the Atreides way and becomes a Harkonnen," says Villeneuve. "It's one of the most powerful moments of the film. All of the sophistication and vulnerability of Paul Atreides is gone. We see in his eyes the madness of war."

A dangerous spark is lit.

At the end of 'Dune 2,' Paul Atreides becomes the version of himself he most feared

Villeneuve says Paul would never have killed the nearby Emperor, who was also key to his dad's death.

"He would have looked like a coward to kill the old man and there would not have been the proper passage of power," says Villeneuve. "Paul takes revenge, but it's controlled."

Paul first seeks to marry The Emperor's daughter Princess Irulan (Florence Pugh), vowing to "rule together over the empire." A true power couple.

Rather than fight the Emperor, he calls for a champion. Feyd-Rautha jumps at the chance to be the Emperor's champion in battle. Paul dispatches the bald baddie in a climactic battle and Princess Irulan agrees to marry him to spare her father. The throne is Paul's.

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The truly altered Paul follows this with an act that his innocent past self had reoccurring nightmares about. He declares war against the approaching armada of powerful Houses intent on thwarting his exploding power. Paul knows from his own dreams that this sparked holy war he's just started will kill billions (with a B) of people.

"This hunger for revenge that resides in Paul resurfaces and gives him the strength for this final attack, knowing it will open the door to chaos and ultimate catastrophe," says Villeneuve. "There will be a holy war fought in his name. It's a match into a gasoline tank, a very high price to pay for this revenge."

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Fremen Chani (Zendaya) is the only one horrified by the emergence of the supremely powerful new Paul Atreides, who had been her lover and comrade. Before the political Princess Irulan proposal, Paul told Chani, "I'll love you as long as I breathe." And he means that in a highly compartmentalized way.

Naturally, she's shocked by the proposal, which happens right in front of her, and doesn't bow down to the new ruler. Neither does Princess Irulan, as the two standing women look at each other and Paul.

The disillusioned Chani, who had fought to protect Paul from his dark destiny, is last seen alone in the dunes calling for her sandworm out of town.

"Part Two" ends with Chani's perspective, which is "fundamental" to making the point that "Dune" author Frank Herbert made in his second book in the series, the cautionary "Dune Messiah."

"Frank Herbert was very concerned that people saw 'Dune' as a celebration of revenge and of Paul Atreides as a great leader," says Villeneuve. "He wanted 'Dune' to be a warning against charismatic leaders and messianic figures. Paul is not the hero, but the antihero."

The director says he's "profoundly happy" with the Chani-focused ending of "Part Two," calling it "the only way I could end the movie slightly differently from the book, but very close to the intentions of Frank Herbert."

Will there be a 'Dune 3'?

As "Dune: Part Two" looks to conquer the box office this weekend, the probability of a third installment being greenlit is about as obvious as an approaching sandworm. But Villeneuve is loathe to discuss "Dune: Messiah," which he says is in the screenwriting phase, other than saying it will also be a faithful adaptation of Herbert's works.

"Movies are fragile dreams in the early stages," says Villeneuve, who shot the first two "Dune" movies back-to-back in the desert. "It was very inspiring, but taxing physically. Frankly, my concern isn't whether 'Dune: Messiah' will be greenlit, it's that I need to rest. I will do it if there's a very strong screenplay, and it's not there yet."