In the 1920s English seaside town, WICKED LITTLE LETTERS unfolds as a mysterious comedy based on a true story. Conservative Edith Swan (Olivia Colman) and boisterous Irish migrant Rose Gooding (Jessie Buckley) receive scandalous letters filled with profanities, causing a national uproar. Rose is accused of the crime and a trial begins. However, townswomen led by Police Officer Gladys Moss (Anjana Vasan) suspect there's more to the case and that Rose may not be the culprit. This riotous mystery explores the scandal impacting everyone in the town.