In 1997, Christopher Smith was combing the shelves of a library in Fort Washington, Pennsylvania, when his interest was piqued by a volume simply entitled John Newton.

A history buff who was then toggling between a career as a police officer and social worker, Smith thumbed through the biography. He became intrigued by the subject, who as a young man worked as a British slave trader, but eventually became a leading abolitionist..
“There was all this great drama, and then I get to the end of it, and, by the way, this guy wrote the words to the song ‘Amazing Grace’,” recalls Smith nearly two decades later. “This complicated man had written what may be the best loved song in the western world? My jaw dropped.”

When Smith collected himself, he set off on a voyage of discovery that would lead him to be the composer, lyricist, and co-book-writer, with Arthur Giron, of Amazing Grace, the Broadway musical opening July 16 at the Nederlander Theatre after development at Goodspeed Opera House and a successful tryout in Chicago last fall. The epic, with a cast of 31, traces the astonishing conversion of Newton from callous slave trader to fierce abolitionist. His miraculous change of heart is reflected in the opening lines of his song:

Amazing grace! (How sweet the sound)
That sav’d a wretch like me!
I once was lost, but now am found,
Was blind, but now I see.

Says Smith, “The heart of the musical is whether people who do terrible things can truly change, if you can ever reclaim what was good in your past. This is one of the essential yearnings of human beings: Can I be loved in spite of my faults? Can I be forgiven for the things I do that hurt people?”

In the musical, Newton’s path to redemption is rocked by the traumatic early death of his mother and a troubled relationship with his father, a British captain; it is smoothed by the care and affection of two characters — Mary Catlett, his idealistic love interest, and Thomas, his devoted African manservant from the time he was 9 years old. In the starring role of John Newton  is Josh Young, a Tony nominee for his Judas in the recent revival of Jesus Christ Superstar. Trying to rein in his rebellious spirit are Tom Hewitt, as his father, Erin Mackey, as the beautiful and patient Mary, and Chuck Cooper, another Tony nominee (The Life), as the long-suffering Thomas.

While Catlett is based on a historical character, Thomas is an invention, a composite based on slave memoirs of the time. Born in Sierra Leone and scarred by his own guilt and shame, the slave becomes the linchpin in the musical, the lens through which the adventures of Newton are observed. At one point, Thomas heroically rescues his master from drowning, a deed his owner eventually repays by callously relegating him to a worse servitude in Barbados. The show is unflinching when it comes to depicting the corrosive and inhumane effects of slavery, both on its victims and its perpetrators.

Director Gabriel Barre said that it was important not to sidestep the brutality of the story and Newton’s participation in it if his conversion was to carry emotional clout. “We had to have the courage for the piece to find its way,” says Barre.  That includes the unusual spectacle of an African princess,  played by Harriett D. Foy, who sells her own people into slavery.

Such paradoxes do not escape either Smith or Barre including the ones surrounding the composition itself, most notably that a song written by a former slave trader should first achieve popularity in the American South as a folk hymn and source of consolation among those he sold into bondage. They both note that through the ages, “Amazing Grace” has become  something of a Rorschach test, appropriated equally by secular and ecclesiastical forces. It has been as much at home at the funerals of Martin Luther King Jr. and Nelson Mandela as at such lovefests as Woodstock. It became a political anthem in demonstrations against the Vietnam War.

But in the musical itself, the song achieves its power as a spiritual instrument of redemption and forgiveness. That grace is hard-won. It only comes through a sea change in the behavior of a man who cries out for mercy in the middle of a life-threatening storm. The recriminations are not easily accepted. Given Newton’s conduct regarding Thomas, there is little reason for the slave to forgive his master.

“Forgiveness is a very difficult thing to exercise and to understand,” says Barre of that most mysterious of consolations. “Thomas needs to see proof of John’s change of heart, not just words or idle chitchat. It is one of the most difficult moments in the show to justify and make real for people.  But it is also one of the most potentially moving.”

Smith sees a parallel for Thomas’s behavior in another epic, Les Misérables, in which the bishop forgives Jean Valjean for stealing the silver candlesticks. “It’s the humane thing to do, to give someone a second chance,” says Smith of the musical that he has been obsessed with for years and that he says has bestowed its own special grace upon him. “John Newton did some terrible things, but he turned his life around. Bearing witness to that change can be inspiring to anybody.”

Thro’ many dangers, toils, and snares,
I have already come;
’Tis grace hath brought me safe thus far,
And grace will lead me home.