This movie tells a bit of the story of John Newton (1725–1807), who wrote the lyrics to Amazing Grace. But it is mostly about the movement inspired by the song and by the tireless work of William Wilberforce and others who worked to end slavery.
See this movie. It is brilliantly beautiful.
Also, I think this movie is appropriate for children as young as 8.
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.
'Twas Grace that taught my heart to fear,
And Grace my fears relieved;
How precious did that Grace appear,
The hour I first believed!
Through many dangers, toils and snares,
We have already come;
'Tis grace hath brought me safe thus far,
And Grace will lead me home. (Lead me home!)
The Lord hast promised good to me,
His word my hope secures!
He will my shield and portion be,
As long as life endures.
Yea, when this heart and flesh shall fail
And mortal life shall cease,
I shall possess within the veil
A life of joy and peace.
The earth shall soon dissolve like snow,
The sun forbear to shine;
But God, who called me here below,
Will be for ever mine