Rosemarie DeWitt (Little Fires Everywhere) has been cast in HBO Max’s true crime series The Staircase, according to Deadline. DeWitt will star opposite the show’s previously announced leads, Toni Collette (Unbelievable) and Colin Firth (Supernova).

The eight-episode limited series will tell the story of Michael Peterson (Firth) and the criminal case against him in the wake of his wife Kathleen’s (Collette) suspicious death, according to Deadline. DeWitt will appear as Kathleen’s sister, Candace Zamperini.

The Staircase is based on the Jean-Xavier de Lestrade’s Peabody Award-winning docuseries from 2004 as well as books and reports about the case, according to Deadline. Three new episodes of the docuseries were released in 2018 as a follow up to Peterson’s case. The episodes premiered at the Tribeca Film Festival and were later made available for streaming on Netflix alongside the original episodes.

Dewitt last starred opposite Collette when she played Collette’s sister in Showtime’s United States of Tara. Her TV appearances include The Last Tycoon, Olive Kitteridge and Mad Men. She recently starred in the films The Professor, Arizona and Song of Back and Neck.

Deadline reports that Antonio Campos (Christine) and Maggie Cohn (American Crime Story) are set as the writers, showrunners and executive producers of the series. HBO Max and Annapurna TV are co-producers.