If you go back to the earliest days of his career — Gates of Heaven and Vernon, Florida — Errol Morris’ great gift appeared to be giving voices to people on the margins of American society.

Morris’ interests have shifted or evolved somewhat since then. Sometimes he’s issue-driven and sometimes he’s determined to get under the skin of famous and notorious figures. There isn’t always a simmering rage driving his filmmaking — his last outing, The Pigeon Tunnel, was pretty close to hero worship. But it’s become more common than the curious empathy that fueled his first works.

The prolific director’s fury is at a full boil in his NBC News documentary Separated, which is now getting a fall festival showcase. Examining the border policy of family separations, Morris rips into the xenophobes who stealthily crafted it, the unqualified bureaucrats who set it in motion and the paranoid climate that could allow it to resurface depending on how the November election goes.

On an intellectual and reporting level, Separated is sturdy and persuasive. Morris is angry, and if you’re watching this movie, chances are good that after 90ish minutes, you’ll be angry, too.

What Separated needs, though, is a little touch of the old Errol Morris. The film replaces the voices of the actual people impacted by the family separation policy with generic composite characters who exist only in sterilized reenactments. It plays solidly to the head, but misses the heart and soul entirely.

Adapting the book by NBC News’ Jacob Soboroff, Morris is careful to emphasize that as much as Donald Trump and Stephen Miller might be the heavies of the piece, the general inhumanity of our border policy has existed for decades regardless of the party in power. Still, he’s equally careful to distinguish between the stumbling blocks imposed by previous (and subsequent) administrations and what was rolled out during the Trump presidency.

Morris builds his timeline and his case convincingly enough that you won’t fret that he’s a couple of years behind on the reporting for this particular story, previously chronicled in Soboroff’s 2020 book and multiple documentaries and docuseries.

There are heroes, including Jonathan White, a top official and attempted whistleblower in the Office of Refugee Settlement, who was given the impossible task of trying to reunite separated families. White is candid and unflinching and never gives any sense of a political ideology as he explains the need to protect and care for children at our borders, regardless of how they got there. That’s basic human stuff. But he explains how a government apparatus meant as a program for unaccompanied minors became a way to strip children from their parents in the name of deterrence, and how facilities meant as temporary holding areas became overcrowded institutions.

Morris, frequently presented as an off-camera voice, calls the de-parented children “state-created orphans” and includes footage from David Lean’s Oliver Twist for good measure.

“Harm to the children was part of the point,” White laments, echoing claims by most of the career administrators who agreed to Morris’ typically impeccable Interrotron treatment.

To nobody’s surprise, Miller wouldn’t sit down for interviews. Nor would Trump or former Homeland Security Secretary Kirstjen Nielsen. They all look horrible here, but it’s hard to imagine them caring. (Elaine Duke, Nielsen’s predecessor in an “acting” capacity, is present mostly to confess that she was relieved she didn’t get the full-time gig.)

Giving every indication that he’s never sat through a full Errol Morris film, Scott Lloyd, the former director of the Office of Refugee Resettlement, makes an easy villain. He’s squirmy, forgetful and generally incapable of giving a straight answer to any direct question. His former bosses will surely appreciate that he doesn’t narc, but there’s no chance that he will generate ambivalent reactions. He’s just a cad.

One thing White says about the separated children struck me. He observes, “They’re not a metaphor. Each of them is an actual child.”

Why, then, does Morris choose to treat the traumatized families as symbols? As characters in a carefully composed diorama? Throughout Separated, we’re following “Gabriela” and her son “Diego” (played by actors Gabriela Cartol and Diego Armando) as they come up from Guatemala. Their death-defying trek is restaged in beautifully shot, entirely bloodless fashion.

Morris’ two composites don’t have personalities or backstories or voices. They’re not people. They’re shells of people and I have no idea why he decided this was a better approach than finding an actual mother and son who were separated at the U.S.-Mexico border and later reunited, and interviewing them. The reenactments feel like reenactments, without specificity. The stories they replace — the tangible horror of the journey, the Kafka-esque procedural nightmares, the conditions within the facilities themselves — aren’t provided elsewhere.

As distancing devices go, I far prefer the way Morris compares the border wall to the old zoetrope. But other than unexplained snippets of animation, Separated doesn’t use or explain that technique at all. I can try: The light let in by the slats in the zoetrope helps bring still images to life. What does that mean for little fictionalized “Diego”? Nothing.

Instead, the slats in the wall and the zoetrope made me think of the light that Morris fails to let in here, from the people on the fringes of American society who could really bring Separated to life.