A word of warning, reader, if you’re considering seeing “These Shining Lives,” a drama opening Friday at Cascades Theatre in Bend: You’ll want to bring tissues. And maybe a handkerchief. And maybe, just to be safe, have some spare tissues handy for those who didn’t see or heed this warning.

The play by Melanie Marnich (also known for TV writing on shows including “Big Love”) is no weepy melodrama. It’s based on the tragically true story of four Ottawa, Illinois, women who are among what came to be known as the “Radium Girls” due to their exposure to harmful radiation. They were exposed on the job, which entailed painting watch faces with glow-in-the-dark paint containing radium for the Radium Dial company, which according to the play employed 1,000 women in 1922, the year in which the story begins.

And if the play began and concluded in 1922, it would be a much happier affair: A housewife gets a job, makes new friends, earns her own money and ups her happiness, improving the quality of her life and the lives of the people she loves. It would serve as a love letter to unfettered capitalism.

As it stands, however, “These Shining Lives” follows the chronology through to the bittersweet end, with a case that went all the way to the Supreme Court, as Radium Dial mulishly refuses to concede wrongdoing.

The play, directed by Emily Cady, follows the life and career of Catherine Donohue, played by Kimberly Leemans, as she gets a job to help her and her welder husband, Tom (Caleb Neet), make ends meet. The smitten parents of two are sweet, playful and endearing, which is among the first signs your tear ducts will be in for a workout later (tissues, people).

The year is 1922, and Catherine, who also goes by Katie, is thrilled with her new job at Radium Dial, where she’s assigned to sit with three other women. She receives a chilly reception from the competitive Charlotte (Natalie Manz), but witty Pearl (Megan Flanagan) and moralizing Frances (Betsy Alexander) more readily accept her into the fold, teaching her the quickest method of painting, which involves using one’s lips to keep the brush at a fine point. Painting speed is critical as they’re paid by the watch.

Katie actually has concerns about putting radium to her mouth — besides the awful taste. As anyone who saw the Alan Alda play “Radiance” a year and a half back in this same theater can attest, radium is radioactive, and a little bit harmful. Here, Katie’s worries are expertly dismissed by the company doctor (Matt Vigil), who touts the health benefits of radium. Why wouldn’t she believe a medical professional?

For all too brief a time, life is good for the workforce heroines, even if they are being watched by their intimidating boss, Mr. Reed (Robert Flanagan).

Radium serves as almost another character in the play, and at first it is a wonder. Its dust gets on Katie’s clothes and hair, and Tom warms to the way she literally shines. Sure, she may be a little more tired, but the extra income is welcome, and Tom is there to take up some of the domestic slack. When she sees the company doctor about her complaints, he prescribes aspirin.

But as act one draws to a close, Katie’s concerns grow.

“I ache, Tom. My body, my bones, my back. I’m scared,” she says. “There’s something wrong.”

Katie knows something is off, but has to work to convince Tom, and the effort to get her colleagues to speak up about their own health problems isn’t much easier.

All the while, Reed — who, like the doctor, represents the company and its interests, not those of the girls — digs in his heels.

“This is a good company,” he says more than once, but the truth will come out. The women go to see the independent and truthful Dr. Dalitsch (Adam Haaga), who levels with them about their health, and eventually a lawyer, Leonard Grossman (Levon Alldredge), who cares more about what’s right than money. He takes the case, with Katie as the lead plaintiff.

During a break in rehearsal last week, director Cady spoke in glowing terms (too soon?) about her cast, including Neet,” whom she describes as “a pleasure to watch.” She also cited Leemans’ impressive résumé, which includes appearances on “The Walking Dead” and “Nashville.”

“You can’t take your eyes off of her when she’s on stage,” Cady said. “Every single person who has committed to this show made a solid commitment from the beginning. I’m just blessed with an incredible cast and crew, and everybody just pouring their hearts into making it the best that it can possibly be. When you’re telling a true story, you’ve absolutely got to do it justice.”

Though some dramatic liberties have been taken, she said, “It’s a real watch company. All of these women in this show are real women who existed. … There are no fictitious people, really, in this at all.”

As a result of Katie’s willingness to go after Radium Dial in the face of public and media scrutiny, “Their actual trials and so forth made it all the way to the United States Supreme Court,” Cady said, adding that the women’s plight led to improved safety regulations for workers.

Cady then warned this reporter of the next scene, in which the four women learn the truth about their medical conditions from Dr. Dalitsch.

“This is a tough scene,” she said, “so get your tissues ready.”