We know the hymn. Atheist or Christian, Buddhist, Muslim or Jew, you’d be hard-pressed not to have stumbled across it somewhere.

“Amazing grace! How sweet the sound

That saved a wretch like me!

I once was lost, but now am found;

Was blind, but now I see.”

But even if you know the words, you probably don’t know who was lost, the “wretch” who was saved, the man who wrote it. And you don’t know how he, and his song, changed the world.

That hymn’s unknown history, its place within the first civil-rights movement – the abolition movement in 18th-century Britain – is the subject of “Amazing Grace,” an emotionally engaging drama from a director famed for his screen biographies and his sermons.

It’s about William Wilberforce a devout man of firm conscience who mixed evangelical zeal with political savvy and shook up Britain’s parliamentary system in the late 18th century – and galvanized a good portion of the British public – with his long and determined crusade.

In “Amazing Grace,” that fight – against slavery, and against the shipping and trade industries in Britain that relied on slavery for their commercial well-being – is depicted in simple (but not simplistic) strokes, with the accordant powdered wigs, horse-drawn carriages, stately mansions and fancy dress of a self-respecting period drama.

Sturdily directed by Michael Apted, from a screenplay by Steven Knight, “Amazing Grace” stars Ioan Gruffudd as Wilberforce, presented here as a reluctant pol who had to be swayed from the priesthood so he could fight the good fight in the corridors of power. Allied with William Pitt (Benedict Cumberbatch – there’s a name!), destined to become the youngest prime minister in British history, Wilberforce lobbied, strategized and eventually out-flanked a powerful band in the Houses of Lords and Commons who supported slavery for the economic good of the land.

Wilberforce’s chief opponents, and “Amazing Grace’s” chief villains are the contemptuous Lord Tarlton (Ciaran Hinds) and the Duke of Clarence (Toby Jones, who played Truman Capote in the lamentably little-seen “Infamous”). Albert Finney appears briefly as John Newton, a Wilberforce mentor beaten down by politics and corruption, and now living as a monk. Rufus Sewell, eyes a-shine and hair a-long, plays a nutty grassroots abolitionist, while Youssou N’Dour, the African music star, is a freed slave whose published accounts of his ordeal helped to galvanize the anti-slavery movement.

Framed as a flashback, and a romance, “Amazing Grace” unfolds as an older, wearier and not altogether well Wilberforce describes his parliamentary maneuverings to a lovely lady (Romola Garai) whom he’s been set up with by friends. She’s passionate about politics and just causes, too, and as they stroll the gardens and share a divan by the fire, the film flips back to the story at hand.

The scene-stealer here is the man who wrote the hymn that changed the young politician. Albert Finney is John Newton, ex-slave ship captain, the “wretch” turned preacher and hymn-writer. Here is the guilt, the heartfelt grief over the “20,000 ghosts” he transported to the Indies that the movie begs for.

It’s a natural story for director Michael Apted, who has made documentaries on American Indian activists, the student uprising in Beijing and gorilla-protector Dian Fossey in between James Bond popcorn pictures.

The movie’s shortcomings are in its limited focus. This is the fight, as fought, in Britain. The slave trade itself is kept abstract, with empty (but stinking of death) slave ships and empty manacles as props for speeches. It’s the way the average Briton, civilian or Parliamentarian, would have known the trade, but the movies can be expected to make it more vivid, give slavery more of a human face.

Apted opts not to show the horrendous cruelty inflicted on thousands upon thousands of captive Africans, shackled and chained, making their way to the Americas in ships. Instead, he has Wilberforce and his fellow abolitionists describe the inhumane conditions – in the precise, passionate language of legislators who believe that human decency is more important than money and power.

“Amazing Grace” arrives as Hollywood-slick, a polished British period-piece. It manipulates, but then again, so does the song that gives it its title. And movies, like hymns and history, should give us a good cry, every now and again.

Roger Moore of The Orlando Sentinel also contributed to this review.
AMAZING GRACE

3 stars out of 5

PRODUCED BY: Edward Pressman, Terrence Malick, Patricia Heaton, David Hunt and Ken Wales, directed by Michael Apted, written by Steven Knight, photography by Remi Adefarasin, music by David Arnold, distributed by Samuel Goldwyn Films.

RUNNING TIME: 1 hour, 56 mins.

RATED: PG (adult themes)

STARRING: William Wilberforce/Ioan Gruffudd

William Pitt/Benedict Cumberbatch

Barbara Spooner/Romola Garai

John Newton/Albert Finney

Olaudah Equiano/Youssou N’Dour