VENICE – I didn’t intend to wait four days to review “Night Moves” — not least because, in the wake of her last three features, a toothpaste commercial directed by Kelly Reichardt would be high on the year’s most-anticipated list — but the combination of cumulative screenings and the slackening effects of illness kept pushing it unintentionally down the to-do list.

Yet if any film on the Lido this year belongs on the back burner, it’s this one. That may be the lousiest compliment I’ve given a good film all year, but it’s a compliment nonetheless; for the more time Reichardt’s latest has to let its calculatedly flat terrors work on the brain, the more imposing and guileful an achievement it seems. “Night Moves” is a pretty slow burner while it’s on the screen; off it, it’s stubbornly inextinguishable, the trick birthday candle of this year’s Venice fest.

That’s already three fire metaphors too many for a film that itself never feels quite up to body temperature. Even its three highly recognizable leads look unfamiliarly sallow and freeze-dried — a real-world “Twilight” ensemble without all that fussy eyeliner. And if none of this sounds like poster-ready praise, so be it: “Night Moves” is a film that lives or dies by its chilliness, its reticence, its small but nut-hard surfaces, dealing as it does with individuals who have no inclination to explain or excuse their most questionable decisions. It’s a moral film, but not a moralistic one; unfailingly human, but not always humane.

Certainly, even amid the soured, toughened ensemble of “Meek’s Cutoff,” Reichardt has never presented us with characters quite as hard to like as this central trio. Josh (Jesse Eisenberg) and Deana (Dakota Fanning) are a pair of environmental activists seeking more heroic fulfilment than the granola virtuousness offered by their positions at, respectively, a farming commune and a hippy-crystal spa. You can hardly blame them for wanting to get away from this talk-over-action world, wickedly satirized by Reichardt and regular co-writer Jon Raymond in early scenes of excruciating student enviro-conferences.

At no point does their alternative plan — to blow up a local Oregon dam, as a tough-love demonstration to their fellow man of his excessive consumption of natural resources — sound like a sensible or admirable idea. We certainly don’t warm to the scheme with the addition to their outfit of opaque, ex-military explosives expert Harmon (Peter Sarsgaard), whose reasons for participating don’t even seem misguidedly principled.

In Reichardt and Raymond’s elegantly bisected narrative structure, these nascent eco-terrorists are impenetrably cool customers until, suddenly and catastrophically, they’re not. Mapped out with the director’s customary care and deliberation, this is a film of two even acts, with no need for a third. Over the first hour, Josh, Deana and Harmon methodically plot, prepare and finally execute their act of extreme vandalism; over the second, relations between the separated accomplices unravel as they face the ugly, unforeseen human consequences of their silly stunt.

Played with appropriately wan, quivering intensity by Fanning, Deana turns from glass to tissue as her impetuousness catches up with her at an accelerated rate. Hers is the steepest emotional ascent, so it’s interesting that Reichardt, in the film’s later stages, sticks largely with Josh, whose nervous collapse is less visible but no less dangerous to the collective: in the best dramatic showcase for his sullen, nervous intelligence since his Oscar-nominated Mark Zuckerberg in “The Social Network,” Eisenberg gives a performance highly calculated in its inexpression, variable posture and eye contact giving away what the set of his mouth will not.

To call “Night Moves” Kelly Reichardt’s first thriller isn’t inaccurate. Certainly, the musty, HD-grey textures of Christopher Blauvelt’s cinematography and atonal twang of Jeff Grace’s score are working toward a kind of homemade noir aesthetic in the same way that “Meek’s Cutoff” stripped the Western down to great-wide-open elements. As in that film, Reichardt isn’t hurried along by genre expectations, telling this potentially shrill story in her own time and tone. Indeed, at 112 minutes, this is actually her most languid film to date; I do wonder how much more it would pinch the nerves in her formerly standard 80-minute format.

But if Reichardt hasn’t previously made thrillers in the strictest sense, the pervading atmosphere of distrust and disorientation here is far from unfamiliar. “Night Moves” (sinister if second-hand title and all) outdoes its predecessors for shock and shadow and human peril, but her films have always been fuelled by uncertainty: the precipice of fatherhood in “Old Joy,” the search for lost companionship in “Wendy and Lucy,” the end of the trail in “Meek’s Cutoff.”

Much of the uncertainty in “Night Moves” concerns matters of criminal consequence for its protagonists, but there’s a political ambivalence to her storytelling here that feels newest of all. Where her past work has been subtly, non-forcibly liberal (even the seemingly depoliticized “Wendy and Lucy” worked in a few sly digs at the Bush-era economy), “Night Moves” is a film expressly about the hazards of ill-considered leftist excess, here given lethal symbolic agency. Reichardt certainly hasn’t gone conservative on us, but after a series of films that have underlined the occasional benefits of community, this slowly, steadily unnerving one expounds the virtues of being on your own side.