Dan Stevens (Downton Abbey) has been cast in the Watergate series Gaslit at Starz, filling the role Armie Hammer (Call Me By Your Name) was set to play, according to Variety. Stevens joins previously announced Academy Award-winners Julia Roberts (Erin Brockovich) and Sean Penn (Milk) in the anthology drama based on the real-life political scandal.

Gaslit, based on the award-winning Slate podcast Slow Burn, will focus on “the untold stories and forgotten characters of Watergate,” according to Variety. These characters include White House Counsel upstart John Dean (Stevens), Arkansan socialite Martha Mitchell (Roberts) and Nixon’s trusted advisor, John Mitchell (Penn).

Variety announced that Hammer left the Starz drama last February, but no reasons were given for his exit. Hammer has recently stepped away from several projects—including The Offer at Paramount+ and the romantic comedy film Shotgun Wedding—after controversial social media posts were leaked online and allegations of sexual assault surfaced, according to Variety.

Starz declined to comment, Variety said.

Stevens is perhaps best known for his role as Matthew Crawley in the hit British series Downton Abbey. His television work includes the FX and Marvel series Legion, High Maintenance, and Kipo and the Age of Wonderbeasts. He recently starred the films I Am Your Man, Eurovision Song Contest: The Story of Fire Saga, and Disney’s Beauty and the Beast remake.

Gaslit will be helmed by creator and show runner Robbie Pickering (Mr. Robot) and is set to start production this spring. Executive producers include Sam Esmail (Mr. Robot), Matt Ross (Silicon Valley), and Julia Roberts (Eat Pray Love) via her company Red Om Films.