Octavia Spencer has signed on as executive producer on the independent anti-slavery movie “Mumbet,” Variety has learned exclusively.


“Mumbet” will be directed by Alethea Root (“Part Time Fabulous”) and produced by Kim Waltrip (“Hit & Run”) of Wonderstar Productions and Root of Truth 13 Productions.


The script, written by Stephen Glantz (“Wunderkinder”) is based on the book “A Free Woman on God’s Earth” by Jana Laiz and Ann-Elizabeth Barnes. Casting has not been announced.


Mumbet was also known as Elizabeth Freeman, who was the first enslaved African American to file and win a freedom suit in Massachusetts after hearing the words in the newly ratified state constitution — “All men are created free and equal.” In 1781, the Massachusetts Supreme Judicial Court found slavery to be inconsistent with the State Constitution — a ruling to have implicitly ended slavery in Massachusetts.


“This is a woman who risked her life to speak truth to injustice,” Root said. “The power of truth is paramount and the time is ripe for the world to be inspired and moved by Mumbet’s story.”


Spencer received her third Academy Award nomination this year in the best supporting actress category for “The Shape of Water.” She won an Oscar for “The Help” and was nominated for “Hidden Figures.”


“I’m extremely proud to be a part of helping to tell such an important story,” Spencer said. “It’s time for everyone to know about Elizabeth ‘Mumbet’ Freeman.”


Filming will take place in the area where the story unfolded in the Berkshires of western Massachusetts. Elizabeth Aspenlieder, “House of Cards” actress Jayne Atkinson, Glantz, and Libby Heimark are also executive producing “Mumbet.” “Mumbet” has the support of State Rep. William “Smitty” Pignatelli, who played a role in extending the state’s tax film incentives.


“It’s hard to beat the architectural history and scenery we have here, and having the support of the state enables us to film in the very locations this historic event occurred,” Atkinson said.


Spencer is currently repped by WME and Jackoway, Tyerman, Wertheimer, Austen, Mandelbaum, Morris & Klein.