“Magpie” screenwriter Tom Bateman doesn’t want you to guess his film’s twist ending; he wants you to squirm.

“I want an audience to just be nudging their boyfriend, girlfriend, mum or dad like, ‘Something’s wrong here. There’s something up,'” he says with a laugh.

“Magpie” follows married couple Anette (Daisy Ridley) and Ben (Shazad Latif), whose lives begin to fracture when their daughter is cast in a film alongside a glamorous movie star, Alicia (Matilda Lutz). As Anette’s suspicions of Ben’s infatuation with Alicia intensify, their secrets and lies burst to the surface, culminating in a jaw-dropping finale.

Bateman, an actor known for his work in projects including “Murder on the Orient Express” and “Behind Her Eyes,” makes his screenwriting debut with the captivating neo-noir thriller directed by Sam Yates. He penned the script based on an idea from wife and star Ridley,...