“Aquaman” actor Yahya Abdul-Mateen II is in final negotiations to join Aaron Sorkin’s “The Trial of the Chicago 7,” sources tell Variety.

His casting in the historical drama follows the news that the long-awaited film is finally moving forward with Paramount Pictures on board for domestic distribution and Cross Creek signing on to finance and co-produce alongside Amblin Partners.

The movie is based on the infamous 1969 trial of seven men charged by the federal government with conspiracy and inciting to riot, a result of the counterculture protests in Chicago at the 1968 Democratic National Convention. The trial transfixed the nation and sparked a conversation intended to undermine the U.S. government.

Abdul-Mateen will play Black Panther Party co-founder Bobby Seale, who was one of the original eight that were charged. Seale’s case was eventually severed from the other defendants, leading to the “Chicago Seven” moniker. He was bound and gagged in front of the gallery and jury by order of the presiding judge, and was sentenced to four years in prison for 16 counts of contempt of court for his continued outbursts during the proceedings. While still in prison, he was put on trial again as part of the New Haven Black Panther trials in 1970 over the murder of Alex Rackley, a Panther who had admitted under torture to being a police informant and was subsequently murdered. Seale was alleged to have ordered the killing; the trial eventually ended in a mistrial.

Abdul-Mateen joins a star-studded cast that includes Eddie Redmayne, Sacha Baron Cohen, Jeremy Strong, Frank Langella, Mark Rylance and Joseph Gordon-Levitt. Sorkin will direct from his own script with Marc Platt, Stuart Besser, Tyler Thompson, and Matt Jackson producing. Marc Butan and Anthony Katagas will serve as executive producers.

In addition to his breakout role as Manta in Warner Bros.’ “Aquaman,” Abdul-Mateen portrayed Lupita Nyong’o’s character’s father in Jordan Peele’s hit “Us” and had a starring role in an episode of “Black Mirror.” He will appear as Cal Abar in HBO’s “Watchmen” TV series, which also stars Regina King and Don Johnson.

Abdul-Mateen has also landed the titular role in the Jordan Peele-produced “Candyman,” set for release in 2020, and will star in Netflix’s drama “All Day and a Night” alongside Jeffrey Wright. He is repped by WME and Anonymous Content.