The Snow Leopard author travels through a barren landscape.

Novelist. Travel writer. Explorer. Zen monk. Peter Matthiessen is all of these, and more. But to consider the totality of his life experience and literary achievements is to risk being swept away by the drama of his worldly adventures and, as a result, to lose sight of the fact that Matthiessen’s most important journeys have been of the inner kind, of the human mind and spirit. These inner travels and how they have impacted his life, informed his beliefs and inspired his writing are at the core of this documentary.

No Boundaries reveals a man most comfortable on the outskirts of civilization, among birds and Native Americans, and his writing is often colored by his strong conservationist streak. Shot over the past few years, the movie portrays Matthiessen as a driven man, who, despite his years, exudes a youthful energy. “Peter is one of the most dynamic octogenarians you will ever meet,” says Jeff Sewald, though he also notes that this intensity has sometimes had an alienating effect.

Matthiessen is too much of a free agent to worry about people who disagree with his beliefs or his work (at one point, he laughingly describes his arguments with Random House over their limpid support of his novel Far Tortuga). With time, even his midlife missteps have been corrected: His once-abandoned son Alex, now an adult, appears in the film to pay respect to his dad. Matthiessen’s work on and off the page is powerful and opinionated enough that, through the years, he has made both implacable enemies and staunch allies. But as Sewald says, the author has, at this point, gotten most things right. “Peter is loved and hated by all the right people, and that’s high praise. No one wants to be loved by the scoundrels.”

No Boundaries will air on PBS on April 24.

Photograph: Jessie Close