Changing the world started with something very simple for Mary Pat Laffey: “It just wasn’t fair.”

Laffey, 81, is the protagonist of “Stewardess!,” premiering Saturday at the History Theatre. The unfairness? Gender-specific rules foisted upon her and other “stews” by midcentury Northwest Airlines: weight restrictions and a prohibition against eyeglasses, to ensure that business travelers would find them pretty. Not being allowed to marry. Forced retirement at age 32. Having to share hotel rooms. Being ineligible to be pursers, the best-paid position on the flight crew.

Almost immediately after reporting to work in 1958, Laffey chafed at those rules. Buoyed by the passage of the Civil Rights Act in 1964, Laffey and other flight attendants filed a federal class-action suit in 1970, challenging airline industry restrictions that applied only to women. The case ended 14 years later in the U.S. Court of Appeals with a decision written by Ruth Bader Ginsburg, ordering NWA to pay attendants $59 million and allow them to compete on equal footing with men.

“Mary Pat gradually built an incredible resolve and became a groundbreaking woman in the fight for equality,” said “Stewardess!” playwright Kira Obolensky, who was turned on to the story by History Theatre artistic director Ron Peluso. “And none of us know who she is.”

“Stewardess!” dramatizes Laffey’s battle for equality, weaving in African-American attendants’ fight for civil rights and the parallel story of feminist activist Gloria Steinem, born just a few years before Laffey.

But it’s a comedy, not a lesson.

“I certainly don’t want to hit audiences over the head with inequity,” Obolensky said. “The play is funny and also moving.”

Some of the humor comes from Laffey’s own words (an Obolensky favorite from the play: “I always admired the feminists. Didn’t always love their haircuts.”).

“I think some of the funny comes from the absurdity of it, for us now,” Obolensky added.

“Absurdity” is an understatement: Laffey (who married in 1976, and now goes by Mary Pat Laffey Inman) knew stewardesses who kept their nuptials secret, with special work phones that their husbands couldn’t answer. She knew a woman who, worried about exceeding her assigned weight, worked flights to Japan and back without eating a thing. (At 5 feet 5½ inches, Laffey’s contractual weight was 125 pounds.) There were job interviews where bosses noted, “Her head’s too small for her body.” And when Laffey finally won the right to become a purser, the airline punished her with her first assignment: flying into Vietnam during 1968’s Tet Offensive.

“While Northwest was an excellent airline, its management was also first-class chauvinists,” is how Laffey understated it in a 2014 speech celebrating the 50th anniversary of the Equal Employment Opportunity Commission.

Laffey, who retired in 2000 and lives in Seattle, recalled a conversation with former U.S. Secretary of Defense Melvin Laird. She asked the NWA board member why the airline continued to oppose equality.

“He said, ‘We hope we will be able to appoint more conservative judges who will not look so kindly on this,’ ” Laffey recalled.

Theater as time travel

The minute Obolensky met Laffey, she was reminded of Twin Cities actor Tracey Maloney, with whom she often worked at Ten Thousand Things. Maloney, who snagged the lead role in “Stewardess!,” says it’s a challenge to time-travel back to an era when employer-sponsored weigh-ins didn’t seem bonkers.

“The world is tilting a little bit back in that direction, so you can certainly imagine a taste of what it was like,” Maloney said. “You do have to think, oh, we do worry about our weight and keeping our jobs. We do call each other ‘gal.’ We do have to wear wigs if our hair is too thin.”

Form-fitting stewardess uniforms help Maloney imagine her way back in time, but the scope of the play, which takes Laffey from her 20s to the present, is another challenge.

“We decided early on we had to do our own version of her, not trying to strictly capture what she looks like or her mannerisms, but the spirit of her,” Maloney said. “The thing I keep hearing, over and over, is that she’s so charming and unassuming and optimistic and polite.”

Capturing those traits over 50-plus years is easier said than done, so Maloney requested extra time with “Stewardess!” director Noël Raymond. “John Catron is in it and he told me yesterday he’s playing 19 different characters,” Maloney said. “I’m just playing one, but it’s huge so I requested of Noël that I come in and have some time alone with her, to trace Mary Pat’s journey.”

Describing a play as a “journey” has become a cliché. But it’s uniquely appropriate to well-traveled Laffey, whose daughter says her mom gets “treated like a rock star” when she flies because so many staffers recognize her and want to shake her hand (Laffey’s special request is typically modest: She likes her water without ice, please).

To symbolize Laffey’s journey, Obolensky structured “Stewardess!” as a memory play, with Laffey boarding a plane and looking back on her career.

“The question is how do you tell the story, with the sweep of time? I think I figured that out at Raw Stages,” said Obolensky, referring to the 2017 History Theatre play reading series where a version of “Stewardess!” debuted.

‘Rocks in my stomach’

A theater fan, Laffey said Obolensky has done a “marvelous” job with “Stewardess!” Laffey had been approached by others who wanted to tell her story. But she was put off by demands that she sign away rights to her own life.

“Kira was kind and gentle and I just had faith she would be accurate, that she would portray the lawsuit as a renaissance for women. I think she grasped a mood and a temperament of flight attendants and women, in general,” Laffey said by phone.

The “women, in general” piece is something that only gradually revealed itself to Laffey, whose fight was not just for stewardesses.

In fact, she says the most satisfying aspect of the suit was “that it changed the way employers looked at women. All women, not just stewardesses. They now have to look at potential and at intellectual abilities, not our weight.”

Laffey will be here this weekend to watch parts of her life unfold on stage and participate in a talkback after the Sunday matinee. She says that, even 35 years after the conclusion of the suit, it’s hard to take it all in.

“When I first went to see a lawyer, I was looking for them to honor my seniority and a $10-a-week raise. I was so ignorant of the ramifications,” Laffey said. “During the 15 years, it was tough. I had rocks in my stomach often. I would think, ‘I’m calling the law firm and telling them the whole thing is off. I can’t do it.’ But then I would pause and say, ‘No, Mary Pat. There’s no going back.’ ”

Now, of course, she’s glad she didn’t make that call.

“It turned out I was right. I did have a leg to stand on,” Laffey said. “Women had a leg to stand on.”