Sean Penn has set an ultimatum on the set of the upcoming Starz Watergate series “Gaslit”: either the entire cast and crew receive COVID-19 vaccines, or he’s not returning to work. Although NBCUniversal, “Gaslit’s” studio, imposed mandatory vaccines for “Zone A” cast and crew members (those in close proximity during production), and provided an on-site vaccination clinic for those involved with the production, Penn is putting his foot down. The actor’s representatives confirmed his decision to Variety. 

Penn has offered to facilitate the mandatory-for-all vaccination effort, free of charge, through his nonprofit organization Community Organized Relief Effort.

“Gaslit” focuses on the untold stories and forgotten characters of Watergate, from Nixon’s opportunistic subordinates, to the deranged zealots aiding and abetting their crimes, to the tragic whistleblowers who would eventually bring down the whole enterprise. Penn will play Attorney General John Mitchell, Nixon’s most trusted adviser and best friend at the time. Julia Roberts will portray Martha Mitchell, the Arkansan socialite who was one of the first to publicly sound the alarm on Nixon’s involvement in Watergate, in spite of her affiliation to the president via her husband, John Mitchell.

“Gaslit” is produced by UCP, a division of Universal Studio Group, for Starz. Along with Robbie Pickering and Matt Ross, “Mr. Robot” creator Sam Esmail — via his overall deal with UCP — and Chad Hamilton serve as executive producers under their production banner Esmail Corp. Roberts will executive produce under her banner Red Om Films, along with co-executive producers Lisa Gillan and Marisa Yeres Gill. “Gaslit” reunites Esmail and Roberts, who worked together on the first season of the Amazon series “Homecoming.”

Anonymous Content and Slate’s Gabriel Roth and Josh Levin also executive produce “Gaslit.” Leon Neyfakh, who created the podcast “Slow Burn,” consults on the project. “Slow Burn” has already been adapted into a docuseries at Epix.

“Gaslit” is written by Pickering, Amelia Gray, Alberto Roldán, Anayat Fakhraie, Uzoamaka Maduka and Sofya Levitsky-Weitz. Karen Bailey, executive VP of original programming at Starz, oversees “Gaslit” for the Lionsgate-owned network. The Starz pick-up marked the second Esmail project announced by UCP last February, following the dark comedy “The Resort” from Andy Siara, who wrote the Andy Samberg-Cristin Milioti breakout comedy “Palm Springs.”

Deadline first reported the news.