Some viewers will dismiss the premise of Summer ’04, a love triangle involving middle-aged adults and a precocious 12-year-old, as patently absurd. Others will find the film’s narrative feint, a role reversal between parents and children, too glib to take seriously. Certainly this second collaboration from director Stefan Krohmer and screenwriter Daniel Nocke pushes the boundaries of plausibility and propriety, chronicling a courtship that may or may not countenance adultery, pedophilia and manslaughter.

But what wonderful ambiguity, what cheeky impudence! Summer ’04 not only hedges its bets on what we’d normally consider clear-cut moral matters, the movie also melds incongruous influences to create a fresh form. Imagine, if you can, a sunny noir tragicomedy conjoining early Roman Polanski (specifically, Knife in the Water) with early Eric Rohmer, punctuated by a surprise ending and laden with social criticism. The resulting cinematic chimera isn’t remarkably pretty, but it’s pretty remarkable.

The film’s plot, at least, is straightforward. André (Peter Davor), a political theorist on summer leave from teaching, and his partner, Miriam (Martina Gedeck of The Lives of Others), are vacationing at their cottage near the sea, where they sail boats, play badminton, garden and dine alfresco. Their 15-year-old son, Nils (Lucas Kotaranin), has brought along his girlfriend, Livia (Svea Lohde), three years younger than he but far more mature. André and Miriam are modern parents, however, and treat the teenagers more like grownups, although their benign indulgence comes across as smug condescension.

The quartet’s pleasant idyll is disturbed when Bill (Robert Seeliger), a self-indulgent neighbor with a taste for women and fast cars, strikes up a flirtatious friendship first with Livia, then with Miriam, precipitating a shifting romantic entanglement that confuses the characters almost as much as the audience. Can Bill seriously be pursuing the presumptuous Livia, smart and sassy but hardly prepared for an affair with a roué three times her age? Is Miriam so casual with her affections that she can cheat on André without reflection, and so insecure that she allows herself to grow irrationally jealous of Livia? Why is André so annoyingly passive, so irritatingly critical of Nils, whom he blames for Livia’s behavior? Indeed, Nils alone seems able to maintain perspective on the film’s unfolding events, which threaten to spiral out of control…and eventually do.

Summer ’04 succeeds because Krohmer and Nocke underplay their overwrought scenario. Miriam and Bill, for example, discuss their hothouse passions with the abstract self-absorption of Rohmer’s bourgeoisie en vacance. André, likewise, is fatuously complacent, Livia reflexively bored, Nils studiously indifferent. We know these characters—adults who can’t let go of the irresponsibility of adolescence, adolescents eager to pretend they are responsible adults—so we’re not surprised when they act out, with predictable irony, their improbable fates.

But unlike French metaphysical comedies, Summer ’04 has an undercurrent of cruelty, a disturbing lack of empathy among its sons and lovers. The fatal accident that serves as the climax seems willed, sprung from the distrust that clouds the film’s relationships with tension and anxiety. Apparently, there’s no shortage of schadenfreude to spread around when Germans go on holiday.