“Cartel Land” introduces viewers to Tim “Nailer” Foley of the paramilitary group Arizona Border Recon, who works to disrupt the activities of Mexican drug scouts and couriers. (The Orchard)

There are two sides to every story. Sometimes even more.

By turns fascinating and frustrating, the multifaceted documentary “Cartel Land” opens with a nighttime scene of masked men cooking crystal meth in a remote part of the Mexican state of Michoacán, under the watchful eyes of armed guards. One can imagine how nervous filmmaker Matthew Heineman must have been, especially coming off the relative safety of his last film, “Escape Fire: The Fight to Rescue American Healthcare” (directed with Susan Froemke). “Cartel Land” bristles with so much actual danger, from all sides, that it’s no wonder Heineman is shown wearing a bulletproof vest in publicity photos.

Heineman’s film focuses primarily on the high-risk activities of two men on either side of the U.S.-Mexico border: American Tim “Nailer” Foley of the paramilitary group Arizona Border Recon, whose members work to disrupt the activities of the Mexican drug scouts and couriers who ply their trade along the border; and José Mireles, a Michoacán physician who, at the time of filming, was the leader of an equally well-armed Mexican vigilante group called the Autodefensas, whose mission was to uproot the drug cartels that his country’s own law enforcement officers seem unable or unwilling to control.

“Cartel Land” opens by identifying the presumed bad guys and then switching its attention to the two crusaders who, at first glance, would seem to be working toward the same goal. Gradually, however, it becomes clear that any such duality is an illusion fostered by Hollywood fiction, with the exception of the complex, excellent “Traffic.”

Like that 2001 film from Steven Soderbergh, “Cartel Land” takes on the entire drug ecosystem. That includes everything from American drug customers and the Mexican cartels’ low-level employees — who, with arguably sound reasoning, consider themselves lucky to have a job — to both countries’ top political leaders. Their speeches decry the scourge of drugs, while their policies have so far been unable to stop it.

Dr. Jose Mireles, who at the time of filming was a member of the Autodefensas, a group working to uproot drug cartels, is featured in filmmaker Matthew Heineman’s documentary. (The Orchard)

In between are people like Foley and Mireles. And the latter may not be so morally pure, according to the film. “Get everything you can out of him, and then put him in the ground immediately,” says Mireles, with shocking bluntness, to a lieutenant who is about to interrogate a suspected cartel worker.

Even if you believe that Mireles’s heart is in the right place, the man comes across as something of a smooth-talking slimeball at best, and a murderer at worst. Yet it is Mireles’s second-in-command — an elfin senior citizen nicknamed Papa Smurf, whose power struggle with Mireles is documented in the film — who disturbs the most. By the film’s end, allegations that the Autodefensas, under Papa Smurf, have not only struck a deal with the notoriously corrupt Mexican military but are also funding their weapons purchases through drug sales are but a sliver of the film’s many damning revelations.

If any message emerges from “Cartel Land,” it is one of futility. As one of the film’s participants puts it, the drug war is a “never-ending story.” “War” doesn’t even seem the right word choice here, despite Heineman’s bulletproof vest. “Cartel Land” reveals a culture that spans the border, full of death and dismaying behavior on both sides, but thriving all the same.

R. At Landmark’s E Street Cinema. Contains crude language, drug content, disturbing images and a brief sexual reference. In Spanish and English with subtitles.
98 minutes.