“How many women have to die before it’s a story?” Keira Knightley asks in a new trailer for “Boston Strangler.” Inspired by a true story, the thriller sees the two-time Oscar nominee playing Loretta McLaughlin, a reporter for the Record-American newspaper who is determined to uncover the truth about a mysterious killer.

The spot suggests that Loretta does not have the support of her bosses. “You’re on the lifestyle desk. You’re not covering a homicide,” she’s told. She finds an ally in Jean Cole (Carrie Coon), a colleague who joins her dangerous quest to discover the murderer’s identity.

McLaughlin become the first journalist to connect the Boston Strangler murders.

Knightley received Oscar noms for “The Imitation Game” and “Pride & Prejudice.” Her more recent credits include Camille Griffin’s “Silent Night” and Philippa Lowthorpe’s “Misbehaviour.”

Coon landed an Emmy nod for “Fargo.” She was last seen in “The Gilded Age,” an HBO historical drama that’s been renewed for a second season.

“Boston Strangler” launches March 17 on Hulu.