In his slim book and with dispassionate language, Northup related the horrors he experienced as a slave and even more that he witnessed. Screenwriter John Ridley has been faithful in his adaptation, virtually no "Hollywood" flourishes added. There are no real heroes either, no white knights coming to save the day. Just one decent act by one decent man. Even Solomon, in a finely wrought Oscar-nominated portrayal by Chiwetel Ejiofor, is cast as nothing more, or less, than an honorable man enduring terrible times.

That very nod to veracity, the filmmakers' unwillingness to create artificial martyrs, or hyper-imagined hardships, is part of the agitation.

"12 Years" is not only the story of Solomon Northup, but of a quintessentially un-American institution. We the people may abhor slavery today, yet for so long it infiltrated every sector of life and livelihood in this country. Though the practice was concentrated in the South, certainly in the final years before the Civil War, slavery was not just a Southern problem. Northup's story begins with his kidnapping in the North.

By using the considerable power of film to make slavery so real, the Oscar-nominated director has unsettled us. "12 Years'" characters define physical and emotional extremes: Lupita Nyong'o brings to excruciating life an abused slave's pain; Michael Fassbender is equally adept as the sadistic plantation owner dispensing it. Both earned Oscar nominations for their performances.

PHOTOS: Scenes from '12 Years a Slave'

Harder to bear are the more ordinary exchanges. Benedict Cumberbatch's William Ford in particular. An everyman, as Northup described him, Ford read Scriptures to his slaves on Sunday, and sometimes sided with them against brutal overseers. But he never freed them, and wasn't willing to shoulder the cost of keeping two children with their mother. Exhibiting guilt at every turn, he was unwilling to discard — or concede — its reason.

The more relatable the man who owns another man, the thinner the divide between him and the rest of us, the more terrifying to watch.

Yet that is also what "12 Years" demands with every line of dialogue, every slash of the whip, every humiliation: That we not look away. That we remember this horrific institution existed in our country and was kept viable by some of our own family members.

The racial legacy we struggle with today lives inside "12 Years a Slave." Slavery on our soil is painful to remember, painful to admit, difficult to discuss, almost unbearable to watch — and that is why so many choose not to. It will take more than an Oscar win on Sunday to change that.

betsy.sharkey@latimes.com