With a decades-long filmmaking and travel ban finally lifted by the Iranian authorities, award-winning auteur Jafar Panahi is attending Cannes for the first time since 2003, back when his thriller Crimson Gold won the Un Certain Regard prize. And yet the new movie he’s premiering in competition, It Was Just an Accident, is far from a concession to the ruling regime in Iran. If anything, it’s the opposite: a taut, intricately crafted drama about the traumas suffered by political dissidents and other opponents of power, whether they’re renowned directors like himself or just regular working-class citizens.

Putting aside the self-reflexive storytelling that has marked much of his work since he was first arrested in 2010, Panahi’s latest feature is a straightforward 24-hour narrative staged with his usual attention to realistic detail, and backed by a terrific ensemble cast. Subtly plotted like a good thriller, the movie slowly but surely builds into a stark condemnation of abusive power and its long-lasting effects.

It’s been a while since we’ve seen Panahi make a pure piece of fiction, even if this story of torture, imprisonment and the possibility of revenge feels autobiographical in more ways than one. But compared to This is Not a Film, Closed Curtain, Taxi, and No Bears, in which the director was obliged to play the main character because nobody was allowed to work with him, this more traditionally helmed effort is a throwback to earlier movies like Offside, The Circle or his real-time breakthrough, The White Balloon.

Time is certainly of the essence in It Was Just an Accident, which begins, like so many Panahi flicks, inside of a car. The driver, Eghbal (Ebrahim Azizi), is heading home at night with his wife (Afssaneh Najmabadi) and daughter (Delmaz Najafi) when he runs into a dog, killing the poor pup and wrecking his engine. He manages to make it over to a nearby warehouse to get some help, at which point the film abruptly switches points of view to Vahid (Valid Mobasseri), a worker who spots Eghbal as he heads inside.

Or more like, Vahid hears Eghbal, which seems like a minor difference but will have a major impact on the story that follows. For reasons gradually divulged as the tension begins to mount, the worker follows the driver back to his house, stalking the man until he gets his car towed to a garage the next morning. At that point Vahid literally shifts into high gear, driving by Eghbal in a van, knocking him out and kidnapping him. The next thing you know, Vahid is digging a hole in which he’s preparing to bury Eghbal alive.

If this sounds like the start of a B-grade serial killer flick, what happens in It Was Just an Accident is far more realistic when we learn that Vahid believes Eghbal — a nickname meaning Peg-leg in Farsi — is the intelligence officer who tortured him in prison many years earlier, all but ruining his life. Still, Vahid remains doubtful enough about Eghbal’s identity that he reaches out to a fellow prisoner for confirmation, who sends him to a former detainee named Shiva (Maryam Afshari) working as a wedding photographer.

Soon enough, Vahid’s van is loaded with a handful of victims all seeking revenge on the man who abused them for months on end, seemingly because they did nothing more than voice their grievances against the authorities. The catch, which adds another layer of suspense until the penultimate scene, is that they’re not entirely sure the guy packed into the van is the right person, their only evidence being that he also has an artificial leg. (The sound that alerted Vahid earlier was the squeaking of Eghbal’s prosthesis.)

Panahi uses this set-up to explore the ripple effects of autocratic abuse on several characters who don’t know each other, but are connected by the same persecutor. As the team rides around from day till night — like so many great Iranian movies, this one mostly takes place on the road — we get to hear snippets of what they all went through.

Alongside the ringleader Vahid, whose kidney was badly damaged from numerous beatings, there’s also a bride (Hadis Pakbaten) who ditches her wedding to go after the man who raped and tortured her; and an angry worker (Mohamad Ali Elyasmehr) so out for blood that he doesn’t really care if their kidnappee is the right guy. “Even dead, they’re a scourge on humanity,” he says of all the intelligence officers serving under the regime.

This sounds like dark stuff, and much of It Was Just an Accident plunges into the multiple traumas Vahid and the others have never managed to get over. And yet Panahi inserts sly moments of humor into his tale as well, whether it’s the absurd way events unspool after the opening accident, or else the bizarre situation the five strangers find themselves in, which one of them compares to Beckett’s Waiting for Godot. Later that evening, they cross paths with Eghbal’s family, and suddenly the hostage-takers are rushing a pregnant woman to the hospital, after which Vahid heads to a bakery to buy everyone dessert.

These moments aren’t only there to cheer us up, but to allow Vahid and his crew to contemplate the morality of what they’re doing — to ask whether killing Eghbal, if their captive is indeed Eghbal, ultimately serves a good purpose. This is obviously Panahi’s way of asking those same questions aloud, both as a man who suffered months of unlawful imprisonment and as an artist who couldn’t officially make films for years, even if he found brilliant ways to circumvent the interdictions. His new movie never provides us with a clear answer, suggesting in its hauntingly perfect finale that whether you bury an evil man like Eghbal or not, he will always remain by your side.

Like all of Panahi’s films since The White Balloon, Accident is artfully crafted from the first to the last frame. Cinematographer Amin Jafari — who shot the excellent Hit the Road, which was helmed by the director’s son, Panah (credited as artistic consultant) — captures many scenes in single takes, either riding around in the van or from a fixed position somewhere in the hills above Tehran. The ensemble sequences, of which there are several, feel more theatrical than anything Panahi has made thus far, allowing him to showcase the talents of his cast in ways he was unable to do for decades.

It’s a welcome aesthetic change from all the films the director had to shoot behind closed doors, sometimes with only a tiny video camera. And yet in the end, It Was Just an Accident offers another fascinating case of Panahi turning the camera on himself.