Olivia Colman shilly-shallied her way into American hearts as the inept, insecure Queen Anne in the 2018 movie “The Favorite,” winning an Oscar in the process. Since then, she’s continued to impress with Oscar-nominated roles in “The Father” and “The Lost Daughter,” while also winning an Emmy for playing Queen Elizabeth in “The Crown.” Her new film, “Wicked Little Letters,” may not bring her any awards, yet Ms. Colman demonstrates that even in tossed-off material, she can infuse depths of feeling, levity, and sincerity. 

The setting for the farcical film is the idyllic town of Littlehampton on the southern coast of England, sometime in the early 1920s. Ms. Colman plays Edith Swan, a middle-aged spinster still living with her elderly mother and father in a small row house. On the other side of the wall resides Rose Gooding, a war widow, mother, and recent transplant from Ireland. Conservative and self-effacing where Rose is bold and brash, Edith nevertheless welcomed the newcomer to the neighborhood and the pair became friends.

This friendship, though, is in the past during the film’s opening scenes. Edith has been receiving anonymous letters in which she is ridiculed with profanities and vulgarities. When her father Edward reads out loud the latest letter, the scene is quite funny, particularly because the Swan household is deeply proper and religious. 

Edward firmly believes the letters are Rose’s handiwork, and when he demands the local police do something they promptly arrest her with no real evidence beyond that she’s an inveterate curser and that she and Edith had a falling out. 

Charming flashbacks establish how Edith and Rose’s friendship developed, and how a quarrel Rose started with Edward over his treatment of his daughter distanced the two. Unable to cover bail, the roisterous Rose is sent to prison while awaiting trial for libel. Gladys, a female constable, expresses interest in the case but is repeatedly belittled by her male colleagues and the general public for being a “woman police officer.” 

From Edith’s interactions with her father and Gladys’s inability to get anyone to take her seriously, it’s clear the movie will impart a strong feminist message. The contemporaneous suffragette movement and other women’s rights issues are also brought up, but the filmmakers, including Ms. Colman as a producer, manage to keep the tone light and playful. The film’s satire, though, would appear in sharper relief had more wit been employed and there was less of a reliance on reciting the letters and easy gags.

Religious sanctimony and hypocrisy also come in for a ribbing, especially when Edith begins to bask in the sympathetic press coverage of the case. Yet Rose has supportive forces behind her, too, and when her bail is paid, she is set free before the trial. It doesn’t take long, though, for the obscene letters, which had stopped while she was incarcerated, to begin arriving again, and this time not just for Edith but many other residents of the township as well.

Those refined cineastes hoping “Wicked Little Letters” will turn out to be a British comedic take on the classic poison-pen French film “Le Corbeau” will be disappointed, particularly when the real culprit behind the letters is uncovered. Still, the psychology behind the reveal scans, considering the filmmakers’ depiction of oppressive patriarchy. 

In her aim to comment on gender inequality while also to entertain, director Thea Sharrock is helped immensely by Ms. Colman and the rest of her crack cast, including Jessie Buckley as Rose, Anjana Vasan as Gladys, Timothy Spall as Edward, Eileen Atkins and Joanna Scanlan as local women, and others.

As the briskly edited movie reaches its climax, it careens from histrionic courtroom drama to Keystone Cops-style larks, with plot holes blotting up the story like ink stains from a busted pen. Nevertheless, the movie begins with the words, “This is more true than you’d think,” and one may agree when observing how Ms. Colman gives her character small mannerisms and expressions combining both the sacred and the profane, the faithful and the filthy.