From the film’s producers:

“When illness strikes in the Peruvian Amazon, the person to seek out has traditionally been a curandero. Spanish for “healer,” this skilled practitioner treats everything from bad luck to a bad back. The forest is his pharmacy. His knowledge of native roots, barks, flowers, leaves, is a centuries-old inheritance. It’s much more sophisticated than meets the eye—and unfortunately, with the advance of Western medicine, increasingly at risk of being forgotten.

The curandero is now the first line of defense against many jungle maladies; for much of history, he was the only one. All that began to change when the Spanish conquistador Francisco Pizarro destroyed the Incan empire in 1532. Indian plant healers, likely for reasons of self-preservation, allowed their techniques to blend with Catholic ritual. Resiny billows of smoke, sustained chanting, the laying of hands—it can be hard to know which tradition influenced which.

Of course, one of these traditions has for centuries been thoroughly and at times violently supplanting the other. But the colonizer’s preferred faith and medicine have not won out entirely. Curanderos remain a part of Peruvian culture; they also practice elsewhere in Latin America, in Central America, and even parts of North America, where they are known by several different names.

The curandero has lately been associated with ayahuasca, a ceremonial slurry of botanical elements that draws many a soul-searching Westerner into the jungle. A psychotropic brew, ayahuasca often causes out-of-body experiences, not to mention projectile vomiting.

While they sometimes overlap, the curandero and the ayahuascero are not one and the same. In a northern region of Peru called San Martin, a curandero named Rosendo has been exploring the bodily and spiritual effects of plant medicine for around seven decades. And yet he refuses to use hallucinogens of any kind.

He has been a curandero vegetalista, as he calls himself, since the age of 12. Now in his mid-eighties, he is part psychiatrist, part priest, and a vital part of the rural community. The physical toll of living in these densely forested hills—ranching and farming coffee, cocoa, and bananas—is intense, and Rosendo often treats patients for muscle, joint, and bone pain. His clientele isn’t just local, though. People come from as far away as Lima to ingest his concoctions of boiled leaves, roots, and bark. For severe infirmities, Rosendo will lead a one-on-one session called dietas, which calls for drinking these woodsy tisanes in sessions. The treatments last up to a month or more, and take place in a hut on his small mountain ranch.

If word-of-mouth reviews are any indication, Rosendo’s methods work. Most everyone in the area knows someone whose life was made better by them. But it’s unclear whether his knowledge will be passed down. He is semi-retired himself, having quit full-time healing in order to grow the cash crops from which many of his patients make a living. Though he would like his son, Mauro, to take after him, it is not clear that he will. “The plant teaches you,” Rosendo says. But its lessons, apparently, are not compulsory.”

Rosendo is a curandero, a healer who specializes in natural, plant-based medicines. He has been honing his trade in the mountains of the high Amazon, and at 86, he is one of the last remaining curanderos in the region. Now, he is passing the baton to his son Mauro in an effort to rescue this fading art.