Dominic Cooper goes positively Pacino in “The Devil’s Double,” a film biography of a real-life Iraqi “Scarface” and the poor sap ordered to be his stand-in.

Cooper brilliantly portrays both Uday Hussein, the singularly sadistic son of Saddam, and the fatalistic, fearful Latif Yahia, a former schoolmate of Uday’s yanked out of the army and told to impersonate the dictator’s son so that anybody who wanted to kill him — and potential assassins were legion — would take a shot or swipe at Latif and not the real Uday.

“We could be twins, no?” Uday says when Yahia is summoned to his office. He makes his offer in an instant. “I want you to be my brother. Think it over. You have…ten minutes!”

What the Iraqi heir to Saddam was offering was wine, women and every vice under the desert sun — the trappings of staggering wealth, cars, suites in palaces — and the omnipotence of dictatorial power. To refuse Uday his every desire — your daughter, your bride  on her wedding day, your duty to serve him — was to risk torture and death. There was no one to rein him in, and his appetite for sin and violence seemingly knew no bounds.

“Everything I own will belong to you,” Uday, a buck-toothed version of Cooper (“An Education,” “Captain America”) purrs.

“You are asking me to extinguish myself,” Latif complains. So his old high school classmate has him beaten until he changes his mind.

Lee Tamahori’s film, freely adapted from Yahia’s life story, captures the temptations of a life without rules and without limits, and the horrors of the trap a life lived at the whim of a psychopath truly is.

Hussein’s life in the late 1980s and early 90s was hedonism writ large — sex, drugs, and violence — all in excess. Yahia is shown videos of the Uday’s preferred style of torture, meant to harden the stand-in to the role he was about to play. Yahia tastes the good life and earns the attention of Uday’s favorite (the sexually ferocious Ludivine Sangnier of “Mesrine”), not a smart move. And he struggles to stay on the good side of Uday and Saddam’s chief “fixer,” (Raad Rawi), a man he hopes still clings to some bit of humanity.

Yahia stumbles through the looking glass into a world of doubles on top of doubles (He can never be sure he’s in the presence of the real Saddam.). He clings to his sanity by being repulsed by the madness. He wears fake teeth and is forced into surgery to make the impersonation more real. He never quite manages Uday’s hysterical giggle, but he utterly masters the mercurial rages, the hair-trigger threats, the insolence.

Cooper create two vivid, distinct personalities. The Devil is a preening crazy man whose transgressions are so epic that whenever he injects a little Islamic piety into his speech, “Inshallah” (“God willing.”) — in his voice it sounds like sarcasm. And Cooper captures The Double, a man whose family is safe only as long as he does what he’s told, but a man who comes to see that even that threat has limits to its effectiveness.

Tamahori, working with material closer to his breakthrough film “Once Were Warriors” than anything he’s done in his Hollywood action picture years (a Bond film, a xXx sequel), doesn’t flinch in showing the monster’s appetite for flesh and things of the flesh. And Tamahori doesn’t shy away from depicting the butchery that made Uday a feared and reviled figure in Iraq, somebody who needed a body double simply to survive.

The kinkiness, the temptations and the heartless cruelty are the draws, here. And the ending smacks of Hollywood rewriting of history. But “The Devil’s Double” shows the political consequences of Uday’s misdeeds, the delicate negotiations that keep the people with grievances in line.  And Dominic Cooper delivers a career-making performance, mastering two men, similar in appearance, chained to each other by circumstance and both riding the whirlwind that life in Saddam’s Iraq must have been.

MPAA Rating: R, for strong brutal bloody violence and torture, sexual content, graphic nudity, drug use and pervasive language.

Cast: Dominic Cooper, Ludivine Sagnier, Raad Rawi

Credits: Directed by Lee Tamahori, written by Michael Thomas, produced by Paul Breuls, Catherine Vandeleene and Michael John Fedun, a Lionsgate release. Running time: 1:48