Wandering the grand halls of Scone Palace in Scotland you might stumble on a pretty portrait of two beautiful women in 18th-century clothes, seemingly affectionate sisters. Not so unusual — except one of the “sisters” is black.

Who is that, you might well wonder, as did Misan Sagay, then a young British college student of Nigerian descent, long accustomed to being the only black face in most British rooms. She stopped short upon spotting the painting while touring the palace near her university.

“I was stunned. And taken aback,” says Sagay, now in her 40s and a screenwriter (Their Eyes Were Watching God). The castle brochure named only the white woman in the portrait, Lady Elizabeth Murray. When she returned a few years later, Sagay says, there was more information on the label, naming the black woman as Dido, “the housekeeper’s daughter.”

“So the silent black woman had a name,” says Sagay. “But I looked at the portrait and the way they were touching, and thought, ‘I don’t buy this. There is more to this than meets the eye.’ ”

Indeed there was. Sagay dove into drafty palace archives to learn more, and years later the result is Belle, written on spec by Sagay, directed by Amma Asante, a British woman of Ghananian descent, and starring Gugu Mbatha-Raw,a British woman of South African descent.

READ MORE: Movie inspired by a painting, ‘Belle’ is a true story | USA Today