If you repeat a word too often, it loses all meaning; it becomes air on your tongue, without texture or a tie to anything real. Now say “the border.” In the past four years, we’ve heard about this place so often that it’s become nothing more than a line on a map, a division we are told needs a wall or doesn’t.

What tends to get lost in the conversation is that the border is a wild place, teeming with life. This is what Ben Masters sets out to explore in his new documentary The River and the Wall, which is screening at South by Southwest this week. In his first feature-length film, Unbranded, Masters and three college buddies trained and rode a string of wild mustangs from Mexico to Canada. Once again the Texan filmmaker is embarking on an epic trip through the West; this time he follows the Rio Grande as it unfurls from El Paso, Texas, to the Gulf of Mexico, carving 1,250 miles of the 2,000-mile southern border between the U.S. and Mexico.

Masters and his crew travel by bike, horse, foot, and canoe through some of the country’s harshest and most stunning landscapes. He’s accompanied by Austin Alvarado, a river guide whose parents came to the U.S. illegally from Guatemala; Filipe DeAndrade, a nature videographer who as a child moved with his mother from Brazil to Ohio on a visa that they overstayed; Heather Mackey, a Cornell University–educated ecologist; and Jay Kleberg, a conservationist who is also a sixth-generation Texan. It’s an intense journey. They flood their canoes in rapids. They ride horses down cragged mesas and into an inescapable box canyon in Big Bend National Park. And they encounter what are either drug smugglers or desperate migrants crossing the river. Always present, like a shadowy villain, is the specter of the potential border wall.

The idea for the documentary came to Masters, unsurprisingly, during the 2016 election. He’d been working with a group of biologists studying mountain lions that live near the river, and he began to wonder what a wall would mean for these animals. Then he began to wonder how the hell a wall could even exist in some of the region’s terrain. “I’ve spent a lot of time along the border,” Masters told Outside. “I wanted to see it before they put up their big, ugly behemoth along my backyard.”

As in any good western, the landscape becomes a silent character. We see pan shots of the Rio Grande twisting through canyons deep enough to drive home how infeasible it would be to build a wall there. Then there’s the wildlife, captured with sweeps worthy of Planet Earth. Bighorn sheep drink from the Rio Grande. Migrating birds pause in the lush trees that spread from the banks. And black bears meander near the river, as they have since before a border existed. In the early 1900s, the bears were actually spared by the arbitrary line, finding refuge in Mexico while Texans nearly wiped them out on the U.S. side. Now they’re back, but could they survive with a wall blocking their travel?

The more time you spend with Masters on the trail and in the river, the more you begin to understand that the people who live closest to the U.S.-Mexico line tend to think the wall is a fool’s errand. Yes, it could destroy animal life. But it’s also just a bad idea. The documentary illustrates the point with interviews with everyone from Democratic star (and El Paso resident) Beto O’Rourke to a border-security agent to Republican representative Will Hurd (who bikes part of the way with the group). Hurd, whose Texas district shares 800 miles of border, is in favor of increased enforcement. But, he says, “Building a wall from sea to shining sea is the most expensive and least effective way to do border security.”

In fact, its negative effects are already apparent on the 654 miles of barrier that already exists along the U.S.-Mexico line, thanks to previous administrations. The film could have zoomed out from the visually stunning sections of the border, like Big Bend, and explained what’s already happening in those areas. Endangered Texas ocelots, javelinas, deer, pygmy owls, and jaguars have already seen walls go up in their habitat. Cement barriers and bollard fencing have already shaped migratory routes, and cut people off from the Rio Grande and from their land. If you’re asking “What if?” there are pockets (perhaps not as cinematically grandiose) where this question has already been answered, but the film doesn't spend much time there.

But don’t hold that against the documentary. The question is still as important as ever. As Masters makes his way through the Rio Grande Valley, he speaks with rancher Steve Lamantia, who is all for border security but says a wall would cut him and his neighbors off from the only water around and affect their livelihoods. “People don’t really understand the border,” he says. “They don’t take the time to come down here and look at it.”

The River and the Wall does just that. It reclaims some much needed meaning for the word border—as an ecosystem for wildlife, as a place where people live and work, and as a wild landscape for a great adventure.