The "Pretty Woman" star is reteaming with her "Homecoming" co-creator Sam Esmail for "Gaslit", an adaptation of the Slow Burn podcast's first season, which explored the untold stories and forgotten characters from the events which ended U.S. leader Richard Nixon's presidency in 1974.
Roberts will play Martha Mitchell opposite Penn as her husband and Attorney General, John Mitchell.
Martha was the first person to publicly raise the question of Nixon's involvement in the scandal.
Esmail and Roberts will executive produce the series, which has yet to be shopped to TV and streaming service officials.
The actress made her debut as a TV series regular in psychological thriller "Homecoming" in 2018.