A 1920s English seaside town bears witness to a dark and absurd scandal in this riotous mystery comedy. Based on a stranger than fiction true story, the film follows two neighbours: deeply conservative local Edith Swan and rowdy Irish migrant Rose Gooding. When Edith and fellow residents begin to receive wicked letters full of unintentionally hilarious profanities, foul-mouthed Rose is charged with the crime. The anonymous letters prompt a national uproar, and a trial ensues. However, as the town’s women - led by Police Officer Gladys Moss - begin to investigate the crime themselves, they suspect that something is amiss, and Rose may not be the culprit after all.