Embedded within the obdurate surface of “The Teachers’ Lounge,” the latest film from director Ilker Çatak, is a brand of moralism so elusive it barely knows its name. The German film industry has selected Mr. Çatak’s picture as its entry for Best International Feature for next year’s Academy Awards, citing it as a reflection of “social processes of erosion in the post-factual age.” Our freunde across the way also extol the picture for its diversity, should one take account of such things.

The truth of the matter isn’t quite as modish or ennobling. “The Teachers’ Lounge” is a nasty piece of business. That’s one reason it’s so good. Peg the movie as you will and you’ll end up flummoxed. A stringently configured satire on shifting mores morphs into a tight-lipped psychological thriller that then contorts itself into a deadpan exegesis on the limits of privacy. Fluid and often funny, the movie is also sneaky. It’s the best film I’ve seen in quite some time.

Where does one place Mr. Çatak’s film in the cinematic pantheon? The wiles of academia and the unruly nature of youth have made for provocative fodder going back to Jean Vigo’s “Zéro de conduite” (1933), and probably earlier than that. Given that school is our official introduction to the broader culture and its societal prerogatives, it’s long been a subject rife for comedy, commentary, and caution. That, and childhood is scary.

Or is it that children are scary? Carla Nowak (Leonie Benesch) is a new hire at a German middle school, bringing to the job a bristling, go get ’em energy — in marked contrast to her more seasoned colleagues. She begins each class with a round of rhythmic clapping in order to settle down the students for their lessons. There’s a primness to our Ms. Nowak, but also an abiding respect for those in her charge.

Yet all is not right at school. There’s been a rash of thefts and the administration is hard-pressed to locate who might be responsible for them. Teachers and student representatives engage in uncomfortable meetings about the matter. Individual pupils and entire classes are interrogated by means that test the boundaries of legal protocol. Our heroine is aghast at the methods by which her peers go about trying to uncover the guilty party. 

Ms. Nowak is, in so many words, not having it, and she suffers collegial estrangement as a result. That new teacher — Polish, isn’t she — is a bit of a drag, don’t you think? Frustrated by the continuing string of thefts and eager to do right by her school, Ms. Nowak attempts a surreptitious bit of sleuthing of her own.

Utilizing the camera in her laptop, Ms. Nowak choreographs a situation in which a theft can’t help but take place directly in front of the lens — and, lo and behold, it does. Although we don’t see the culprit’s features, we do watch as someone steals cash from Ms. Nowak’s jacket, and that someone is wearing an ornately patterned shirt. 

Our upstanding paragon of virtue immediately begins trawling the school grounds and spots the telltale garment: it’s a blouse worn by a senior administrator, Mrs. Kuhn (Eva Löbau). That Mrs. Kuhn’s son, Oscar (Leo Stettnisch), is Ms. Nowak’s prize student in no way mitigates her righteousness. She enters Mrs. Kuhn’s office and, after some polite kerfuffling, makes the accusation.

Whereupon follows a nail-biting tale of paranoia and retribution, of good deeds that are punished and then sent spinning wildly out of control. Mr. Çatak’s screenplay, which he co-wrote with Johannes Duncker, navigates the woefully absurd and the deadly serious with a suppleness and wit that is embodied, stride by stride, through Marvin Miller’s stealthy musical score. Although Ms. Benesch is at the center of things, there’s no performance here that outshines another. All the actors, not least the children, are terrific. 

“The Teachers’ Lounge” is discomfiting, riveting, and blessedly out of the ordinary.