You know how it goes: An attractive married couple go out to a party one night wreathed in smiles but return some hours later in stony silence. The shot of the two of them in bed, backs turned toward each other and mutual profiles radiating dissatisfaction in the dark as sirens blare from the street, is a cliche that feels almost as old as cinema itself. And yet the portrayal of this cliche in "Last Night" gets under your skin. Pretty soon, it starts to itch.

Maybe it's the couple who do it to you: Keira Knightley, for once not wearing a period costume, and Sam Worthington, who's been showcasing his capabilities (or lack thereof) outside of the action genre since starring in "Avatar." They play Manhattan couple Joanna and Michael, supposedly sizzling hot for each other but emanating coolish poise, hip to the core and dripping with self-confidence. He's a successful realtor and she's an aspiring writer. He dresses in top-line Brooks Brothers and she wears expensive yet grungy duds.

Just like that, they could walk into a 1990s Woody Allen picture, but two minutes in their company brings out this fact: Joanna and Michael are dull. Their conversations are self-important without being funny, their passion oh-so-artfully contrived. As a Conde-Nast fashion spread, Michael and Joanna are perfect. As a man and woman exploring the boundaries of marital lust, they're perhaps not very effective.