The documentary, titled The Mayo Clinic: Faith, Hope, Science, is scheduled to premiere September 25 at 9 P.M. EST on PBS, and was produced and co-directed by Burns alongside his colleagues Erik Ewers and Christopher Loren Ewers. Burns tells Fortune it will explore each of those individual ingredients—faith, hope, and science—to tell the renowned Minnesota-based hospital’s story.

That story is, indeed, a fascinating one. The institution was born out of a devastating natural disaster—and the ensuing, unlikely alliance between a “Darwinist doctor” and a group of enterprising nuns, as Burns puts it.

In 1883, a massive tornado ripped through English immigrant William Worrall (better known as W.W.) Mayo’s adopted town of Rochester, Minnesota. Mayo and his sons took it upon themselves to lead a re-building effort to help their friends and neighbors.

That fateful decision led to the Mayos’ meeting with the Sisters of Saint Francis—a convent led by one Mother Alfred Moes—which helped take care of patients injured by the storm. But the partnership wouldn’t end there. Mother Alfred told Mayo, the seeming skeptic, that she’d had a vision from God instructing her to build a hospital that Mayo would direct—a facility that would one day become “world renowned for its medical arts,” in Mother Alfred’s words.

Mayo, a man of science, was skeptical at first. But the rest is history. The institution the two built is now regularly cited as one of the best hospitals in America by groups like U.S. News & World Report. Fortune has placed it on our Best Places to Work list on several occasions. It’s the epicenter of groundbreaking scientific studies and has been the refuge of patients like the late Sen. John McCain and the Dalai Lama alike (both of whom are interviewed in the upcoming documentary).

“I didn’t set out to give a wet kiss to the Mayo Clinic,” says Burns. “I’ve been making films about quintessential American stories and people for more than 40 years… What I came to find is the Mayo Clinic’s story is a wonderful, complicated mixture of American ingredients.”

Burns tell me that what may be most impressive about the Mayo Clinic’s “secret sauce” for treating patients is that, well, it’s not a secret at all. “It’s something they’re willing to share from the beginning: Focus on the patients and take care of each other.”

Just how does that translate into the real-world business of medicine? Burns mentions several examples, such as Mayo’s nonprofit status, the possibility that an organization employing salaried physicians and surgeons may be more apt to collaborate with each other and put patients first, and the group’s willingness to innovate on—and even take a contrarian approach to—conventional medical practices.

“You hear the origin story, and it’s nice. But then you dig deeper and see it’s not just a nice story—those founding ideals are at the heart of it,” says Burns.

You can watch the documentary tonight on PBS.

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