The story of finding the story begins in a library in the Georgetown section of Washington, D.C.

James H. Johnston saw a portrait of an African-American man. And he noticed the date, 1822. Such a painting – of an African-American decades before the Civil War – is rare.

Johnston was curious. He asked questions, dug into documents, and pursued leads. Eight years later, he had a book, “From Slave Ship to Harvard: Yarrow Mamout and the history of an African American Family,” which came out in 2012.

“It’s a true story,” he says, “and to my knowledge I’m the only one who’s been able to trace an African-American family’s arrival on a slave ship to today.”

Johnston, an Independence native who now lives in the Washington area, is coming to town to tell the family’s story. He’s speaking at Lincoln Preparatory Academy on Friday and the Black Archives in Kansas City on Saturday.

On Sunday, he’s at the Truman Library in Independence. The event is at 1 p.m., with a presentation, book signing and wine reception. The event is free with admission to the library ($8 for adults, $7 for seniors, $3 for children). The library is at 500 West U.S. 24.

The man in the painting is Yarrow Mamout. He was from what is today Guinea in west Africa. He was a Muslim, and he was educated.

“And no one ever thought that anyone who came on a slave ship could read or write,” Johnston said.

When Yarrow Mamout was 16 – in the middle of 18th century – he was sold into slavery. He endured that for 44 years until his third owner freed him, in 1796.

He prospered: He bought a lot in Georgetown and put up a house. He owned stock in a bank.

“He’s a brickmaker, among many things. He’s quite successful,” Johnston says.

He also was able to buy his son’s freedom.

Yarrow – by a Muslim custom, he put his surname first – was well known in the community, and he came to the attention of Charles Willson Peale, a famous portrait artist of the time who painted presidents and others. Yarrow liked to jokingly tell people he was 140 years old, and that seemed to catch Peale’s fancy.

It was a second, later painting of Yarrow that Johnston saw in the library. “I went home and Googled him, and then I found the Peale portrait,” he says, and with that he knew he was on to something.

The research was slow.

“A lot of blind alleys, and you’ve got to pay a lot of attention to detail,” Johnston says. Records were often hard to come by. A signature of Yarrow’s helped, and that’s the sort of visual aid – he has dozens – he’ll weave into Sunday’s presentation.

The family line continues through Yarrow’s daughter-in-law, and Johnston found them in the Baltimore area. It was a descendent who attended Harvard, graduating in 1923.

There is a current movie – “12 Years a Slave,” nominated for best picture in the Academy Awards coming up in a few weeks – that is based on a true story and tells a similar story. An African-American – a free man in New York in the 1840s – is sold into slavery by friends who betray him, gaining his freedom 12 years later. That man, Solomon Northrup, later wrote a book that became well known at the time.

Johnston suggests a similar treatment for his book.

“I think it should be a movie, and I think it should at least be a stage play,” he said.

Also at the Truman Library, Sunday is the last day of the current temporary exhibit, “The American President.” It has 70 photographs of presidents, taken from Associated Press photographers. It’s also free with museum admission.