Movies about sex should be messy and confusing, filled with human foibles, but too often they are utterly strait-laced.

"The Overnight," an exceptionally well-cast new movie from writer-director Patrick Brice, gets it right. It's a high-concept sex comedy, centered on a long and increasingly weird night shared by two couples as their kids sleep upstairs, and it works because it's more invested in psychology than high jinks or titillation.

Adam Scott and Taylor Schilling star as Alex and Emily, recently relocated to Los Angeles and invited for a pizza night by the quirky Kurt (Jason Schwartzman) and Charlotte (Judith Godrèche).

Needless to say, the pizza isn't really the point, and as the night goes on, it's increasingly apparent that Kurt and Charlotte might be hoping for more than new friends.

The movie is very slight, clocking in at under 80 minutes, but it's ideally structured for a film that is predicated on two couples learning truths about themselves over the course of an intense experience. There's no time to waste.

And with the film unfolding almost entirely within Kurt and Charlotte's palatial home, Brice has ample opportunity to let the dynamic take shape and evolve.

The movie really depends on the actors, of course. Scott offers an offshoot of his nerdy archetype, though rendered with a deeper sense of self-loathing than you might have found on "Parks and Recreation." Schilling is the sensible one and Godrèche has fun playing up Charlotte's desperation.

The real star of the show is Schwartzman, long since established as one of our funniest and most offbeat character actors, who is given free reign by Brice to infuse the film with manic energy.

His work sharpens the satire immeasurably, mocking Kurt's bohemian ethos and abundance of quirks (an affinity for lavish portraits of a very private part, for example), with an undercurrent of genuine loneliness.

It's the sort of over-the-top but precisely calculated work, at once absurd and humane, that's right for a film about what U2 once called the "fever" of desire.