Once upon a time when the world was broke, there were soap operas, so-named because the big soap companies sponsored them for homebound housewives. The shows began on radio, with only mournful organ music for background. One, “Our Gal Sunday,” which became a national hit, asked the question each day, “Can this girl from a mining town in the West find happiness as a wife of a wealthy and titled Englishman?” Millions wanted to know.

Movie star Barbara Stanwyck made a soap movie called “Stella Dallas,” a poor gal who had a baby girl, and when it occurred to Stella that her baby couldn’t reach the high windows of society with her trampy mamma holding her back, she gave the baby away. There wasn’t a dry eye in the house. I know. I was there in my mother’s lap.

Lucky for us, Ken Eisen, program director for the Maine International Film Festival, a man with a penchant for the classic, almost “lost” films of that genre, brings to the MIFF screens “Her Sister’s Secret,” by one of the great old melodrama soap directors, Edgar G. Ulmer. Cue the organ music. Get out your Kleenex.

“Her Sister’s Secret” is set in the New Orleans of 1941, as the war is breaking out. It tells the story of beautiful Antoinette “Toni” Dubois, (Nancy Coleman) a wealthy but lonely New Orleans girl with a searching heart.

The film opens with the Mardi Gras of 1941. While seated on a balcony overlooking Bourbon Street with her boring date for the evening, our masked heroine, Toni, flashes her eyes toward a dashing young army private, Dick Connolly, (a young Phillip Reed) on a nearby balcony.

Dick is smooth but sincere. She’s intrigued. They dine, they dance, they take a carriage ride in the moonlight. This is New Orleans moonlight, pale, cloud streaked and seductive.

One thing, as one thing always does at Mardi Gras, leads to another. The next morning at breakfast in a cafe, and not looking the worse for frolicking in the foliage, they make a date for three weeks hence.

Of course Dick is called up. Toni awaits. He doesn’t show. He sends a note, but it gets lost in the dishes. She leaves. We are now deep in Soap Land. We want to leave too, but some ancient soap opera fan DNA holds us fast.

A disillusioned Toni goes to see her sister in New York, (Margaret Lindsay, a big star of the era who had her own soaps to make) who is married to Bill, a naval officer (the endearing Regis Toomey) who also is shipping out. Here, Toni reveals to her sister the “secret” we jaded viewers and my mother were onto an hour ago. She is with child. What to do? An unwanted baby in New Orleans society? Sans organ, director Ulmer manipulates us with Hans Sommer’s strings and Franz Planer’s art deco camera angles.

A deal is made. Sister Renee, who is unable to produce issue, agrees to take the baby and pass it off as her own, even to hubby when he comes home from the war. Off the siblings go to a resort in Arizona, where little Billy is born and sent home with Renee. Cue the violins.

Four years later, the war is ending. Dick comes home to the cafe in New Orleans, but his Toni has vanished. He follows a clue to New York and finds sister Renee and forces the secret from her. “Poor thing,” he gasps, “She went through all of that without me.”

Meanwhile, unknown to either of them, sister Toni has been stalking the little boy and his nurse in Central Park for months, pretending to be a friend. She gets to hold the child in her lap, and then finally tries to make a break and run off with him. The nurse intercedes and reports the incident to sister Renee, who knows damn well who the stranger is.

Here is where, in the radio soaps, a strong, sensitive narrator intones a question or two: Will Renee return the child or stand her ground? Will Renee tell Toni that Dick is back in town? Will Dick find Toni? Tune in tomorrow at this time and find out.

And while you’re waiting, try some of our detergent on that dirty laundry.

Thankfully, we won’t have to wait. Not all is resolved at the finale of “Her Sister’s Secret,” but no eye leaves here dry.

“Her Sister’s Secret” is no “Stella Dallas,” and Nancy Coleman is no Barbara Stanwyck. But like a yellowing album found in the attic, it has a strange charm.

J.P. Devine is a former stage and screen actor.