Chiwetel Ejiofor stars in Steve McQueen’s “12 Years a Slave.” Courtesy of CIFF.

American cinema has never shied away from depicting human atrocity through a historical prism, though the history is rarely that of its own country. Nearly 150 years after the abolition of slavery, it’s still considered taboo for filmmakers in the U.S. to seriously explore the ways in which racism is embedded in the fabric of our culture. Whenever films do tackle slavery, it’s either in the form of exploitative revenge fantasies (“Django Unchained”) or sentimentalized mush (“The Help”) designed to comfort predominantly white audiences with the delusion that discrimination is a thing of the past.

One of the most impressive things about Steve McQueen’s “12 Years a Slave” is that it is neither exploitative nor sentimental. It is the most unflinchingly honest and wrenchingly authentic portrayal of slavery ever made in America, cementing the British auteur’s status as one of the greatest living directors. His previous two features, “Hunger” and “Shame,” were haunting meditations on a central theme, favoring tone and texture over plot and dialogue. Based on Solomon Northup’s 1853 memoir of the same name, “Slave” has the rhythm and structure of a traditional narrative, though the script by John Ridley is so eloquent and deftly nuanced, it would make a fitting double bill with Tony Kushner’s “Lincoln.”

As a free man drugged and sold into slavery circa 1841, Northup is the perfect guide for modern viewers into this nightmarishly oppressive prison. Since life as a devoted New York family man and accomplished violinist is all Northup knows prior to his kidnapping, slavery is as alien and appalling to him as it is to us. 16 years after making his film debut in Spielberg’s “Amistad,” Chiwetel Ejiofor delivers the sort of effortlessly commanding, ultimately shattering performance that just might earn him his long-deserved status as a household name. McQueen somehow manages to convey the horror of slavery without relying on gratuitous gore. The most upsetting violence in “Slave” is purely psychological, as tyrannical plantation owners distort Bible verses to justify their righteous domination of servants.

Many familiar faces are among the ensemble, but unlike in “The Butler,” they don’t populate the frame merely for the sake of stunt casting (though I admittedly could’ve done without the saintly cameo from executive producer Brad Pitt). These are marvelous character actors at the top of their game, making the most of their screen time by illuminating provocative facets of the era rarely seen onscreen. Consider Alfre Woodard’s sublime turn as a Southern black mistress who has attained the wealth and status necessary to avoid a life of picking cotton, or Adepero Oduye (the breakout star of “Pariah”) as an enslaved woman unable to overcome the grief of being torn from her children. This unconscionable event is witnessed in one of many exemplary Steadicam shots orchestrated by Sean Bobbitt (“The Place Beyond the Pines”), a tour de force of staging, timing and impeccable acting.

Even the film’s abundance of white racists aren’t reduced to one-note caricatures. Each have contrived their own rationale for slavery, from Paul Dano’s insecure bully to Paul Giamatti’s business-minded opportunist (asked whether he gets sentimental when selling mothers and children to different masters, Giamatti sneers, “My sentimentality extends the length of a coin”). Most fearsome of all is the slave-owning sadist played brilliantly by frequent McQueen collaborator Michael Fassbender, who becomes infatuated with his most diligent slave (an unforgettable Lupita Nyong’o), much to the seething chagrin of his wife (Sarah Paulson). This story thread eventually erupts into perhaps the film’s most galvanizing sequence, an excruciatingly protracted lashing in which Northup is forced to participate.

Though McQueen cuts back on his signature use of long stationary takes, when he does choose to utilize them, their impact is staggering. As Northup is hung on a branch just high enough for his toes to caress the ground, the camera maintains a considerable distance, as fellow slaves slowly mull about their work in the background, too fearful to come to his aid. The sheer length of this shot, coupled with Northup’s barely audible yet agonized wheezing, caused my own neck to feel constricted. Rather than drown the imagery in a generically gritty, de-saturated palette, Bobbitt’s Oscar-worthy cinematography is awash in the captivating colors of the Louisiana landscape, which maintain their beauty even in the midst of such dehumanizing barbarity.

As great as this film is, it’s hard to determine just how enormous an emotional impact it would’ve had if Ejiofor weren’t at its core. He is the foundation that grounds every scene with a clear-eyed perspective overcome with outrage. It’s nearly impossible to watch the film’s final moments without feeling the visceral charge of Northup’s overwhelmed tears, as he finds himself suddenly faced with the past he left behind. Aside from Hans Zimmer’s execrable music (which shamelessly rips off his “Inception” score to an obscene degree), this is a near-perfect masterwork that revitalizes faded history with an immediacy and poetry that only a genius like McQueen could’ve pulled off. It’s a two-hour film, but it feels like three, and I mean that in the best possible way. In order to truly understand Northup’s suffering, the audience must be made to feel the grueling length of those twelve years, and McQueen spares us not a single day.

“12 Years a Slave” screens Sunday, October 13th at 7pm. For tickets and other festival info, click here.