The camera is positioned in the sky, godlike, gazing down at a mass of people covered in red material. What is it – paint? Blood? The camera cranes downward at a deliberate pace, slowly focusing in on a smaller and smaller portion of the teeming crowd of red people until the substance makes itself clear: It’s tomato sauce, and the event in question is the Tomatina Festival in Spain, where some 40 metric tons of the ubiquitous fruit are squashed and splattered all over festivalgoers each August.

This documentary footage is positioned at the very beginning of “We Need to Talk About Kevin,” a much-anticipated art-house thriller that opens on South Florida screens today. Logically, there is no connection between this mesmerizing, single-shot sequence and the narrative that follows it, but texturally, it sets the tone for a movie that is constantly being painted red.

Shortly after the Tomatina, we see Eva Katchadourian (Tilda Swinton, who received a Golden Globe nomination for this performance) walking out of her house, which is streaked with blood from an unknown tragedy. Red appears later in the form of strawberry jam, spilling out from a child’s sandwich like an animal’s entrails. Later, when she is petrified of a fellow-shopper in a supermarket, Eva hides in front of a wall of bright-red cans of tomato soup, the kind that may, in fact, have covered Tomatina enthusiasts from head to toe.

The film’s Scottish director, Lynne Ramsay, who has directed two wonderful, indelible films in 1999’s “Ratcatcher” and 2002’s “Morvern Callar,” is a visual stylist par excellance and an exacting visionary. Like Michelangelo Antonioni used to do, she is clearly painting her surroundings whatever color fits the tone of the film, even if said color is not “natural.” Red, and all the emotions that come with it, is the medium, the message and the method of a film about madness.

Told in a labor-intensive, nonlinear pattern and based on the best-selling novel by Lionel Shriver, the movie follows the struggles of Eva and husband Franklin (John C. Reilly, not given much to do here) to raise Kevin, a boy who appears to be a psychopath from conception. Ramsay films his birth through distorted medical mirrors, accentuating his freakdom before he enters the world. And when he does, he is pure malice and manipulation, terrorizing his mother while laying phony, sociopathic charm on his naïve father. It’s only a matter of time, we realize, before this problem child becomes a violent adult, with his climactic actions justifying much of the mystery that has preceded them.

Ramsay is a radical storyteller, but this time, her complex visual rhythms appear to be largely for naught. Too often, she lets the sensational aspects of her story trump the intellectual and logical ones, relishing in horror-movie theatrics that in a Wes Craven film would seem natural but in a Lynne Ramsay movie come off as condescending to her perceptive audience.

“Kevin” swings from a movie that shows us tantalizingly little to a film that reveals too much, without the profound psychology that went into such great teen-violence films as “Zero Day” and “Elephant.” At one point, Kevin (played as a young adult, chillingly, by Ezra Miller) rants to his mother, “Do you think they’d be watching me right now if I got an A in geometry?,” which sounds like Ramsay is using her character to implicate viewers for their disposable consumption of human tragedy. But by the time it winds down, “We Need to Talk About Kevin” has become just that kind of tawdry entertainment. Ramsay tries to have her mores and eat them too, which is a shame considering what a ravishing visual stylist she is.

“We Need to Talk About Kevin” opens Friday at Regal Shadowood 16, Living Room Theaters at FAU and Regal Delray Beach 18, as well as select theaters in Broward and Dade counties.