This quietly eerie, hauntingly enigmatic psychological thriller from the maker of “With a Friend Like Harry” (2000) is by no means a conventional suspense movie; its spirit is more that of a Patricia Highsmith novel, concentrating on mood and character more than plot. It certainly has its share of surprises, but they’re mostly of a sort that deepen the pervasive and sinister ambiguity instead of resolving it. Indeed, the disclosure of one of the two major mysteries at the center of things, which proves quite natural and indeed rather obvious, is likely to come as a distinct letdown. Conversely, the second big revelation satisfies in spite of (or perhaps because of) the fact that it’s essentially irrational and profoundly strange, inviting more questions than it answers. All of which means that you have to be ready to buy into the film’s weird sensibility for it to work its odd but real magic on you. Otherwise you’re likely to find it a very frustrating couple of hours.

“Lemming” is basically a study of the deconstruction of a personality–that of Alain Getty (Laurent Lucas), a self-possessed, confident design engineer at a high-tech firm in southern France. Married to the petite, engaging Benedicte (Charlotte Gainsbourg), he spends his days working out the kinks in his latest project–a remote-control camera housed in a tiny helicopter that you can use to keep an actual long-distance eye on problems that develop in your house when you’re away. Alain’s idyllic life begins to unravel when his boss Richard Pollock (Andre Dussollier) and his wife Alice (Charlotte Rampling) visit for dinner one night. They arrive late, and the remote, rude Alice is in a foul mood, accusing her husband of philandering and causing a scene. The next day she arrives at Alain’s lab and offers to go to bed with him–an offer that he rejects, but not before allowing her to kiss him. Then Alice visits Benedicte unannounced and…well, to say anything more of this would spoil things.

But there’s a second problem Alain must face. It involves a rodent that had gotten lodged in the kitchen sink drain that night, stopping it up; he removes what appears to be the little corpse. As Benedicte discovers the next day, tough, the critter’s still alive, and when she takes it to a vet she’s informed it’s not a wayward hamster, as they’d originally thought, but a lemming–a creature indigenous to Scandinavia that shouldn’t be found in France at all. The mystery of how it made its way into the Gettys’ drain attracts the attention of a specialist on such matters. More importantly, the fact that the creature isn’t what it at first appears to be is thematically related to a change in Benedicte’s personality that follows her meeting with Alice–an alteration that, through a series of odd twists, will ultimately bring Alain to the point of mental and physical collapse–as well as desperate and uncharacteristic action.

This precis is vague, not from coyness but because “Lemming” is the rare picture that swerves from the beaten path so radically that the pleasure it provides largely depends on confronting it “cold” from about the thirty-minute point. But throughout it’s distinguished by writer-director Dominik Moll’s cool, deliberate, almost antiseptic approach to what’s actually rather pulpish material (very like Highsmith in this respect); by the sharply detailed cinematography of Jean-Marc Fabre; and by the edgy, though highly selective, background score from David Sinclair Whitaker. The performances, models of restraint, fit beautifully into the director’s conception, with Rampling’s simmering rage particularly potent. Perhaps some viewers will find it difficult to accept Laurent’s almost preternatural composure as Alain’s woes escalate, but it’s that control that’s supposed to mark the character.

“Lemming” doesn’t employ dark humor with quite the agility that “Harry” did–when it does arise, it’s more subdued and brittle. At more than two hours, it might have benefitted from some judicious cutting. And a turn to the supernatural late in the game may irritate some. But if you’re able to go along with the narrative choice, the overall effect should prove pleasantly unsettling.