Many viewers will find it unbearably sour and distasteful, but “Dog Days,” the debut fiction feature by documentarian Ulrich Seidl, is a masterpiece of misanthropy. It’s the episodic tale of a bunch of residents in suburban Vienna during the most uncomfortable days of summer, when the heat encourages both lethargy and short tempers, and it’s filled with violence and cruelty both paltry and massive–as well as a streak of brutally mordant humor. The film won’t be everybody’s cup of tea, but those who like their brew strong and sugarless may find it grotesquely mesmerizing.

The array of characters on display–most of them irremediably vicious and cruel, but also painfully sad–is wide. An elderly widower (Erich Finsches) retaliates against his noisy neighbors by leaving his lawn mower running aimlessly beside their common fence, obsessively weighs packages from the supermarket in order to complain if they’re a few grams short, and has his aged housekeeper (Gerti Lehner) spend an occasional evening with him, cooking a good meal and dressing in one of his late wife’s frocks before stripping and dancing for his delectation. A mentally deficient hitch-hiker (Maria Hofstatter) drives all those who pick her up mad with her rude, non-stop questions. A security-systems salesman (Alfred Mrva) is being plagued by complaints from dissatisfied customers. A couple (Claudia Martini and Victor Rathbone) who’ve lost a child in an auto accident now live hopeless, pathetic lives separately, but in the same house. A teenager (Franziska Weiss) apparently enjoys being abused by her preening, jealous boyfriend (Rene Wanko). And a middle-aged woman (Christine Jirku) is brutalized by her lover Victor Hennemann) and a grubby pal (Georg Friedrich) he brings to her place with him–though eventually the buddy tries to take vengeance on her behalf.

That moment of revenge is probably the single nastiest, most unappetizing sequence in “Dog Days” (the sight of a man forced to sing the Austrian national anthem on his knees, half-stripped and with a candle stuck in a decidedly uncomfortable bodily orifice), but others come close–not just the strip-tease scene, but also the horrifying fate that befalls the hitch-hiker as the result of the security man’s effort to satisfy his clients. There’s plenty of nakedness on display, but none of it is remotely titillating, since it’s always associated with suggestions of aging, degradation or simple middle-class ennui. Two hours of this are unlikely to endear the picture to most audiences, and even the funny moments are of the most bitter sort. But viewers who are willing to endure some unpleasantness to hear what might be unhappy truths about human nature might give it a try. The appropriately naturalistic performances and the cinematography by Wolfgang Thaler, both gritty and oddly crystalline, are strengths.

A uncompromisingly bleak reverie on human misery and meanness, “Dog Days” is for neither the squeamish nor the depressed. If you have an easily upset stomach, you won’t stay long. And if you go in despondent, you’ll probably emerge in despair, even suicidal. Be forewarned. But if you’re the adventurous type and not easily offended, you might give this cinematic wallow in the depths a try.