The party was a surprise on a warm summer night last week at Misty Meadows Farm in West Tisbury, as about 50 people gathered, drinks in hand, waiting for the arrival of Misan Sagay.

The screenwriter and Vineyard visitor was recently accepted into the Academy of Motion Picture Arts and Sciences, the second woman of color and first African selected to join the writers’ branch.

Henry Louis Gates Jr. spoke. — Mark Lovewell

Ms. Sagay began her career as an emergency room doctor before she wrote and produced the film The Secret Laughter of Women. She wrote a teleplay of Their Eyes Were Watching God which was produced by Oprah. She was inspired to write the script for the film Belle after seeing a portrait of Lady Elizabeth Murray and Dido Elizabeth Belle Murray hanging at the Scone Palace, a historic landmark in Scotland. Research didn’t turn up much about the beautiful woman peering out from behind Lady Elizabeth Murray, so Ms. Sagay filled in the story in.

“She decided at this moment she was going to write this woman’s story, and write this anonymous black lady back into history,” said her friend Henry Louis Gates Jr., who hosted the surprise celebration with Charlayne Hunter-Gault. “And she did it — she really did it.”

Belle follows Dido Belle, the daughter of a British admiral and a an enslaved African woman in the 1700s.

Ms. Sagay said she wants people of color to be more involved in telling their own stories.

“If you have a black woman making a film, you have a black protagonist . . . once you have people of color involved in telling our stories, we’ll be there,” she said.

At the party, her 11-year-old son William shared some of her writing habits.

“I’d come into school and in my notebook there would be a small paragraph of illegible writing scribbled down by my mum,” he said. “It could be the secret to life, or a shopping list, but most likely it’s a part of a script.”

Big hug from friend Charlayne Hunter-Gault. — Mark Lovewell

On one drive to school, she asked, “How do you knock someone out with a pair of clackers?” It wasn’t a threat, it was for a story.

But that’s what makes him love his mom the most, he said.

In his own remarks son J.J., age 14, said the group had gathered not only to celebrate being invited into the Academy, “but the achievement of being a fantastic mother to our family and friend to you all.”

She taught him to love literature and stood by him, even when she was battling breast cancer, he said.

“I hope this Academy membership is just a step in your name being written down in history,” J.J. concluded.

Ms. Sagay is currently co-writing Guerrilla, a six-part television series, with John Ridley.

About joining the Academy as a woman of color and the first African, she said: “I can and must be the first of many.”