Judith Barnard, a freelance writer who stumbled on a second career as a best-selling author at 50, when she teamed with her husband, Michael Fain, a onetime aerospace engineer, to publish a potboiler novel under the pen name Judith Michael, died on May 6 in Chicago. She was 94.

Her death, at a hospital near her home, was caused by heart failure, her daughter, Cynthia Barnard, said.

Combining their first names to create the pseudonym Judith Michael, the couple published 11 commercially successful novels over the years, starting with “Deceptions,” an out-of-nowhere hit, in 1982.

Equal parts romance and thriller, “Deceptions” concerned identical twin sisters — Sabrina, a globe-trotting socialite living in London, and Stephanie, a suburban Illinois housewife — whose fleeting experiment with swapping lives proved to be less fleeting than expected.

Entertaining, yes. A Kirkus review called it “a strenuously inventive, big-budget” romance.

High literature? Not so much. The same review described the book as “glossily seamless nonsense” but noted its potential as fodder for a TV movie — an observation that proved prescient when NBC adapted it in 1985 as a two-part mini-series with Stefanie Powers, of “Hart to Hart” fame, playing the twins.

Then again, their plan had never been to give Thomas Pynchon a run for his money.

Ms. Barnard had already taken a stab at a literary career, publishing her first novel, “The Past and Present of Solomon Sorge,” in 1967. An introspective tale about a Midwestern university professor whose wife of 30 years abruptly abandons him, the book sold only a few thousand copies, leading Ms. Barnard to turn to freelance work on educational films and textbooks, as well as writing articles for Chicago magazines and newspapers.

Her literary horizons expanded after she married Mr. Fain, her second husband, in 1979. “We were looking for something we could do together,” she recalled in a 1991 interview with The Chicago Tribune. “Michael had written technical articles and liked the process but hadn’t found a field he was happy in.”

They began by writing articles about marriage and family for newspapers and magazines, including Good Housekeeping and Redbook. “We had such a good time working together that one day Michael said, ‘Enough of this! Why don’t we write a book?’” Ms. Barnard recalled in a 1999 interview with The Ledger of Lakeland, Fla.

With “Deceptions,” they discovered a winning formula that they employed with many of their following books — what they called universal fantasies, about ordinary, if strong-willed, people who, by a stroke of fate, escape a quotidian existence to taste a life of wealth and adventure, only to face unforeseen challenges along the way.

In “Possessions” (1984), for example, a Vancouver mother of two, whose shady businessman of a husband vanishes, begins a glamorous new life as a jewelry designer in San Francisco, only to fall in with the wealthy family that he had concealed from her.

Similarly, in “Pot of Gold” (1993), a Connecticut housewife must learn for herself whether more money really does mean more problems after she wins a $60 million lottery.

Like their characters, Ms. Barnard and Mr. Fain found their lives transformed by unexpected success. As novel after novel climbed the best-seller lists, they traveled the world to research their books and divided their time between a spacious 16th-floor apartment overlooking Lincoln Park in Chicago and a second home in Aspen, Colo.

Also like their characters, they learned that success can be complicated — in their case, because it required juggling the usual pressures of marriage with the inevitable Lennon-McCartney-style tug of war that comes with creative collaboration.

As Ms. Barnard told The Ledger, “It’s very difficult to have a working relationship with this person who you think has done really dumb things that day and is going to be in your bed.”

Judith Goldman was born on Feb. 17, 1932, in Denver, the elder of two children of Samuel Goldman, who owned a shoe store, and Ruth (Eisenstat) Goldman.

After her parents divorced when she was a child, her mother married Harry Barnard, a prominent historian and biographer, and moved with her children to Chicago.

The family temporarily relocated to Ohio when she was in high school, and she graduated from Fremont Ross High School in 1949. She earned a bachelor’s degree in English from the Ohio State University in 1953. The same year, she married Jerre Papier, an electrical engineer. They divorced in 1970.

She met Mr. Fain by chance at a hospital, where both were visiting his ailing mother, a friend of Ms. Barnard’s. “Bittersweet times, as Michael’s mother was dying and we were falling in love,” she told The Ledger.

Once the couple decided to bet on a publishing career, there was no turning back. “We burned all our bridges, both quit our jobs, lived on our savings for one year,” Ms. Barnard said in a 1997 interview with The Oklahoman newspaper of Oklahoma City.

“We didn’t know how hard it would be,” she added. “We just thought it would be wonderful to work together. And it was, after a while.”

In addition to her daughter, Ms. Barnard is survived by Mr. Fain; her son, Andrew Sharpe; five grandchildren; and a brother, David Barnard.

It helped that the couple adhered to a strict division of labor. After what could be months of plotting and laying down a basic outline together, Ms. Barnard then did the writing, while Mr. Fain served as the editor.

“He’s a superb one,” she said in a 1988 interview with The Houston Chronicle. “And sometimes a harsh critic.”

Each book might require five or six drafts, with endless fiddling. When the inevitable disagreements arose, Mr. Fain, an amateur photographer, would disappear into his darkroom to cool off, he told The Ledger, while Ms. Barnard headed to the kitchen to “knead bread and take out her aggressions.”

Then again, their shared career also proved a marital blessing.

As Ms. Barnard once put it, “It probably kept us married because we always had a book to finish.”