Showtime Documentary Films on Monday unveiled plans for the feature documentary “Attica,” about the 1971 prison rebellion in upstate New York, by director Stanley Nelson.

The movie will debut on Showtime in 2021, the 50th anniversary of the five-day confrontation between prisoners and guards called a riot by some and a rebellion by others. The uprising inspired Al Pacino’s famous chant of “Attica! Attica!” in “Dog Day Afternoon.”

Nelson’s documentary will chronicle the five-day event that turned deadly when armed state troopers stormed the prison facility, leaving 43 people dead and hundreds injured. “‘Attica’ is a film I’ve been itching to make for a very long time. It’s a dramatic story, with so many great voices that have not been heard. The uprising and its aftermath shaped the present in ways I think will be surprising to an audience,” said Nelson in a statement on Monday.

The veteran director’s other films, including “Freedom Summer,” “Freedom Riders” and “The Black Panthers: Vanguard of the Revolution,” have chronicled the African American experience. (SD-Agencies)