Meg Ryan’s son was 10 years old when she first read William Saroyan’s 1943 novel The Human Comedy. It soothed her fears about her boy leaving childhood behind and brought her comfort in the life that is found even in a story about death. Her directorial debut, Ithaca, is based on Saroyan’s novel and comes from a place of motherhood.

“It’s a story that a mother should tell,” the actress told the Gazette in a recent telephone interview.

Meg Ryan's directorial debut Ithaca screens on Wednesday, August 10.

Ithaca follows 14-year-old Homer Macauley (played by Alex Neustaedter), a bicycle telegraph messenger in a small city in 1942 who delivers messages of love, death, pain and joy while hoping for the return of his older brother from the war. Ms. Ryan stars as Homer’s widowed mother and Tom Hanks plays her deceased husband. All the music is by John Mellencamp. Ithaca screens at the Film Center on August 10, followed by a discussion with Ms. Ryan.

Ms. Ryan grew up in Connecticut and visited the Vineyard during the summer. She continues to return to the Island, where she now owns a house on Chappaquiddick.

“We all like to say how terrible [Chappaquiddick] is because we’re so protective of it,” she said.

Though Vineyarders might run into her at the farm stand on Chappy and see her as just another neighbor, for most people Ms. Ryan is a familiar face from the big screen. Her roles in blockbuster romantic comedies including When Harry Met Sally, You’ve Got Mail and Sleepless in Seattle have cemented her into the minds of moviegoers.

But her directorial debut is not meant to be a blockbuster, she said.

“It’s a delicate movie about important things,” she said. “Especially as a parent in this day and age.”

She remembered Sam Shepard, another co-star, saying to her, “Meg, who do you think should tell this story about the making of men? Of course you should be telling this story.”

And in telling the story she couldn’t help but use the lens of a mother.

While adding director to her list of credits, Ms. Ryan was not surprised at the things she did not know, rather the things she already knew. She discovered that while working in front of the camera for so many years, she had unknowingly absorbed knowledge about what to do behind a camera. Saroyan’s writing style in the novel also helped.

“It’s a very filmic novel,” she said. “He speaks in pictures.”

The Human Comedy is not required reading to enjoy watching Ithaca.

In directing the movie, Ms. Ryan used her knowledge of planes and framing from photography. And just as her experience as an actor informed her directing, her new experience as a director informed her acting.

“In the editing room you’re really aware what aspects of performance have more value,” she said. She remembered late nights in the studio trying to make a moment of silence more intense and long talks about lighting for a specific scene.

Though it takes place during a war, the drama of Ithaca focuses on the internal as Homer comes of age just as the world seems to be falling apart around him.

“When the world looks scary you look to community and the cult of your own integrity as a kind of respite from all of that,” Ms. Ryan said. She equated it to the current political climate as well as the beginning of the Iraq war. It’s a story about a small town holding on when world seems scary and unpredictable.

“It’s a little poem really,” she said. “It’s a poem about how fierce and fragile the world is.”

Ithaca screens at the Martha’s Vineyard Film Center on Wednesday, August 10, at 7:30 p.m.; a question-and-answer period with Meg Ryan follows. Proceeds benefit the Martha’s Vineyard International Film Festival. Suggested donation is $15. Visit mvfilmsociety.com for tickets.