In “The Staircase,” which was based in part on a docuseries of the same name, Parker Posey plays the late Freda Black, the assistant district attorney in the murder trial of Michael Peterson (Colin Firth), a wealthy North Carolina writer whose wife, Kathleen (Toni Collette), was found dead at the bottom of their mansion stairs. Black distinguished herself in the courtroom with clownish eye makeup and pearl-clutching appeals to the jury, but Posey told me that she saw more in the character than campy antics. For one thing, Parker had never before played a fellow Southern woman. – The New Yorker