When exiting the theater showing “Ask the Dust,” don’t tell anyone, including yourself, what you thought of the movie.

Give it time to grow on you. And it will. “Ask the Dust” becomes more impressive every time you think about it.

Director and screenwriter Robert Towne’s longtime dream was to bring the late John Fante’s atmospheric novel of 1930s Los Angeles to the screen. The once-forgotten, now-revered novelist created an indelible portrait of lonely people on the fringes of LA’s literary and cinematic circles. None of his characters would have a 90210 zip code, but they are fascinating individuals.

In adapting the Fante novel, Towne accomplishes an extremely difficult feat: He actually makes writer’s block seem exciting. Towne is one of the most literary yet accessible of filmmakers, and every frame of “Ask the Dust” indicates his respect for writers. Even the opening credits have a background of turning pages.

The writer in question, Arturo Bandini (Colin Farrell), has traveled west to make his name in American literature.

To his dismay, he discovers that he can hardly create a sentence. He also discovers that 1930s Los Angeles is rife with prejudice. His landlady (sharply played by Eileen Atkins) crisply informs him that she does not accept dogs, Hispanics or Jews. Bandini is relieved that she at least has no pronounced prejudice against Italians.

The two women who become vital parts of his LA scene, smoldering Mexican waitress Camilla (Salma Hayek) and desperate Jewish caregiver Vera (Idina Menzel), have long been familiar with prejudice. Somewhat to his surprise, Bandini discovers that he is not entirely free of prejudice, and his treatment of both women fluctuates between reluctant tenderness and harsh insensitivity.

Bandini, it seems, is nearly a total innocent. His passion is for words rather than any form of personal contact, but he ultimately proves responsive.

Farrell is surprisingly convincing at registering innocence. But he never shies away from Bandini’s less endearing traits. He also captures the character’s arrogance, petulance and social limitations.

Hayek reveals Camilla’s sensuousness in every gesture, proving more than a match for Bandini in several important areas. She also registers occasional vulnerability and neediness. Menzel, who won considerable praise on Broadway for her roles in “Wicked” and “Rent,” wrenches your heart as the frantic, wounded Vera. Donald Sutherland is eerily effective as Bandini’s shadowy, possibly shell-shocked neighbor. You may think you’re watching his “Day of the Locust” character 30 years later.

Most of the film’s action is internalized, but director Towne creates an exciting earthquake that plays an integral part in the story. He and superb cinematographer Caleb Deschanel create haunting visuals of retro Southern California.

Whether or not you’re familiar with John Fante, if you like novels, you’ll like “Ask the Dust.” It’s melancholy and leisurely, and it’s worth the effort.