Picture Brokeback Mountain crossed with a particularly gruesome episode of Narcos: Mexico, then filled with enough sex and nudity to earn an NC-17 rating, and you’ll get an inkling of writer-director David Pablos’ transgressive new genre flick, On the Road (En el camino).

As tough and uncompromising as that pitch may sound, what’s most surprising about this Venice Orizzonti premiere is how tender and ultimately moving it is. The setting of its unlikely love story is a long highway to hell where death, or possibly worse, lurks just around the corner. And yet amid all the lust, violence, blood and other bodily fluids, Pablos has crafted a deeply felt romance about two men who passionately find each other in a very dark place.

Diego Luna (Andor) is one of the producers of this extreme arthouse entry, and his name may allow it to find some traction outside the festival circuit. The plethora of phalluses on display, as well as a handful of graphic sex scenes, could otherwise hinder its commercial prospects in some places, while perhaps helping it in others.

But On the Road (the less generic Mexican title, which translates to In the Truck, works slightly better) is far from an exploitation flick, even if it’s about the exploitation of men both young and old, whether they’re driving trucks or selling themselves to drivers at rest stops. The film is filled with explicit imagery and moments of grisly violence, but they serve a greater purpose, which is to show how human souls can somehow come together even if their bodies are completely broken.

The story hits the ground running, or more like humping, when we meet handsome young drifter Veneno (Victor Prieto), who’s turning tricks in a roadside gay club that looks like it belongs in Gaspar Noé’s Irreversible. Pablos depicts the sex as raw and unromantic: this is banging, not lovemaking, which makes sense when we realize Veneno earns a living sleeping with truck drivers in exchange for cash or coke, the latter of which he sells on the side.

After one of his clients stiffs him, Veneno runs into Muñeco (Osvaldo Sanchez), a trucker in his 40s who spends long weeks away from his estranged family, drinking and doing drugs to stay awake on the job. He’s hardly a role model, but Veneno quickly takes a liking to the older wayfarer, either because he’s hoping to partner with him or possibly steal his money, or — and this is where the film gets interesting — he’s caught feelings.

The two head down the highway, sitting side-by-side in Muñeco’s massive 18-wheeler. (The phallic symbolism is hardly discreet, especially when Muñeco brags about how truckers are the best in bed because they handle woman like they handle their vehicles.) Veneno doesn’t hide the fact that he’s attracted to the driver, nor that he’s gay, while Muñeco claims he isn’t homosexual, even if he’s not against it and seems curious about what it could be like. The possibilities seem as endless as the road stretching in front of them.

But this burgeoning love story is also a racy, turbo-charged thriller, which means the two travelers soon find themselves in trouble when killers from Veneno’s murky past — seen in stylized violent flashbacks that are explained much later — start chasing after them. At one sordid rest area that’s a graveyard of broken-down trucks, between which a team of female sex workers service their clients, Veneno crosses paths with the driver who stiffed him and winds up stabbing the guy to death. Now the would-be lovers are on the run from both the killers and the cops, leaving them with few viable options.

What’s most impressive is how On the Road turns a boilerplate genre scenario — and one that doesn’t skimp on a bloodbath at the end — into a movie that grows increasingly emotional as things get exponentially worse for its main characters. The more Veneno and Muñeco are in danger, the more their bond evolves from a hard-knocks bromance into an all-out romance. When things are at their most desperate, the two hide out in an abandoned warehouse and slow-dance to the Colombian ballad “Los Caminos de la Vida” (“The Trucks of Life”) in one of the most moving sequences seen this year in Venice.

They also do other things together. Newcomers Preito and Sanchez, both of whom are excellent, bravely display their bodies. Pablos and DP Ximena Amann capture the sex, as well as the many road stops, seedy bars and service station bathrooms, in harsh neon-lit images that underscore the extreme conditions Veneno and Muñeco live in — conditions that apply to all the other Mexicans they run into on this godforsaken stretch of blacktop.

Yet despite its bleak setting and bleaker denouement, On the Road is an unexpectedly optimistic film, even if viewers may want to turn away from a brutal finale. It’s as if Pablos chose to take his lovers deep down to one of the lower circles of hell, just so they could look up and, in the words of Dante’s Inferno, “view the beautiful lights of heaven” for a short time. His movie is punishing and painful, but filled with promise.