Larkin McPhee has never shied away from weighty subjects, taking on nuclear fallout, depression, eating disorders and farmland pollution. But her latest film — a deep dive into the lives of family caregivers — hits close to home.

McPhee's father is 90, her mother 86; neither lives nearby. As they become more frail, McPhee and her siblings have grown increasingly apprehensive. She hears echoes of that "undercurrent of anxiety" all around her.

"It is as if everyone's heart is beating to the same rhythm of concern, worry or exhaustion," McPhee said.

The documentary filmmaker's latest work, "Caring for Mom & Dad," tells the stories of eight families feeling the stress of juggling families, careers and aging parents. Narrated by actress Meryl Streep, the hourlong show airs Sunday at 2 p.m. on KTCA, Ch. 2.

More than 65 million caregivers — nearly a third of all U.S. households — are caring for aging parents. McPhee's film, which includes several Minnesota families, lays bare the financial and emotional toll of the work, which often drains bank accounts, strains marriages and leads caregivers to put their own lives on hold.

"This came along at the perfect time," said McPhee, 54, who first pitched a story on caregiving to PBS in 2008. "If I'd done it six years ago, it wouldn't have resonated with me, with my parents."

McPhee has traveled to the jungles of Venezuela, reported on abducted German bomb makers during World War II and delved into the science of how people and animals use their sense of smell. But finding topics that resonate and push for social change have become the hallmark of her work.

She won a Peabody, TV journalism's highest honor, for shattering stereotypes of depression in a 2008 documentary. Her 2000 film on eating disorders, "Dying to Be Thin," brought attention to rising rates of anorexia and bulimia, and the challenges of getting treatment.

She also has found herself thrust into a high-profile controversy.

In 2010, a University of Minnesota official canceled the broadcast of "Troubled Waters," which explored farming's impact on soil and water along the Mississippi River, and questioned the science. The documentary had been produced and vetted by the university's Bell Science Museum, and the incident became what one U official dubbed "a PR fiasco." The film eventually aired without changes. McPhee, who never doubted her reporting, later earned an Emmy Award.

"It gives you tougher skin," she said.

Documentarian, not doctor

McPhee grew up in Potomac, Md., outside of Washington, D.C., in a family of professionals and creatives. Her grandfather was a doctor, her father a lawyer, and her uncle is John McPhee, the Pulitzer Prize-winning author and longtime writer for the New Yorker.

At Middlebury College, McPhee majored in biology, intending to go into medicine. When she realized she couldn't function without a good night's sleep, she nixed that career path. She jokes that instead of becoming a doctor, she married one. She and Dr. Deniz Perese, an anesthesiologist, married in 1990 and have three children.

Still, that early fascination with science defined her career.

Starting with an unpaid position as a production assistant at C-SPAN, McPhee took a job as a researcher with the PBS television series "Smithsonian World." During a three-year stint at "National Geographic Explorer," she rose through the ranks to associate producer.

McPhee moved to Boston in 1988 and began working for "Nova," the PBS documentary series focused on science and technology. There, she honed her skills as a writer, producer and director, winning an Emmy Award for a program on the impact of the nuclear disaster at Chernobyl, Ukraine.

When her husband landed a job in Minnesota in 1993, McPhee decided to strike out on her own as an independent filmmaker.

"I felt like I was kicking myself out of the nest," she said. "How will I stay alive? No one knows me."

Soon, they would.

She pitched her first solo project to "Nova" on the Mississippi River's "great flood" of 1993, narrated by Hal Holbrook. McPhee called it "the perfect first story" because she got to know the Midwest and to witness the power and beauty of the legendary river.

Science and connections

Those who have worked with McPhee speak of her single-minded focus, and an emotional "unguardedness" that helps her interview subjects open up.

"Larkin is very, very intelligent, and it infuses everything she does," said Matt Ehling, a cinematographer and documentary filmmaker who worked with McPhee on "Troubled Waters" and portions of "Caring for Mom & Dad."

Ehling has watched McPhee find ways to connect with a wide range of personalities, from scientists, to environmental activists, to Louisiana shrimp fishermen.

"So much of the art of interviewing is knowing not only where you are going, but being able to work with the curveballs," Ehling said. "She has a good sense of how to follow those tendrils of conversation and to bring them back to the core of the story."

Paula Apsell, senior executive producer at "Nova," spotted that gift early in McPhee's career.

"She really tells human stories in a distinctive and smart way," Apsell said. "You're not just getting run-of-the-mill interviews with her. You're getting something special."

Streep recognized the emotional power of McPhee's script for "Caring for Mom & Dad," and readily agreed to narrate, said Laurie Donnelly, director of lifestyle programing for WGBH in Boston and the film's executive producer.

Streep and McPhee figured out their grandmothers were both named Mamie, and made an instant connection as a couple of perfectionists who want to tell stories with impact.

"Caring for Mom & Dad" is strategically timed to coincide with Mother's Day. PBS is planning a second showing around Father's Day to give the issue broader attention.

"What we're trying to do is signal a message to people: 'It's happening, pay attention,' " Donnelly said.

With McPhee in the producer's seat, the film packs an emotional punch that has become her trademark.

"She cares," Donnelly said. "She makes television because she wants it to be a catalyst for change."

Jackie Crosby • 612-673-7335