It’s the 1920s and there’s a scandal brewing in the charming seaside town of Littlehampton. Residents have started receiving anonymous, poison-pen letters, brimming with curse words and scandalous prose. Who is writing them and how can they be stopped?

Edith Swan (Olivia Colman) – pious and respected (if not well-liked) – is one of those residents. The letters assassinate her character in the most blue-tinged language imaginable and, when they start to stack up, her autocratic, scripture-quoting father Edward (Timothy Spall) insists the culprit be found. With law enforcement reluctantly investigating, Edith bandies a pet theory that her neighbour Rose (Jessie Buckley) might mean her harm.

Rose is the opposite of Edith: loud, brash, a lover of spirits and dancing, and unapologetic about all of it. When the police arrest her in the letters case, assuming her guilt because of her “loose moral character,” it doesn’t sit well with Police Officer Gladys Moss (Anjana Vasan). With her superiors unwilling to listen, she gathers a group of unlikely yet resourceful female volunteers to get to the bottom of the mystery.

What begins as a village whodunnit suitable for the pearl-clutching set evolves into a profound statement about the stifling social confines around women’s behaviour and their possible tragic consequences. Screenwriter Jonny Sweet provides fabulously sharp dialogue, made even more enjoyable through the talents of the cast.

It’s all brought together by director Thea Sharrock (Me Before You), who makes room for the darker narrative undertones of misogyny, hypocrisy, and repression while keeping the many twists of this story moving at the perfect clip for its comedy.