Reviewed at the 2012 Tribeca Film Festival

As the cab pulls up to her home, she gazes upon it with a look that's equal parts fear and dread. "I'm married," she tells him. "Oh," he replies. "That's too bad." It's bad because they've hit it off so well on the plane and in the cab; it's also bad because he gets out and walks to his home, which is basically across the street. Funny how you never notice a new person moving in, isn't it?

Her name is Margot (Michelle Williams), his name is Daniel (Luke Kirby), and her husband's name is Lou (Seth Rogen), and Take This Waltz is mostly about what happens next between the three of them. It is written and directed, with remarkable delicateness and a deft ear, by the actress Sarah Polley, but after this and her previous feature, the masterful 2006 drama Away From Her, we can probably dispense with calling her "the actress Sarah Polley"; this is a filmmaker, quite possibly one of our finest.

She tells her story of a marriage jeopardized by attraction in small moments and loaded silences, in longing looks and observed behavior. The situation is not presented as simple, nor is it motivated or rectified by big dramatic scenes (in fact, they're studiously avoided, sidestepped or kept off-screen). That look from the cab notwithstanding, Margot is not trapped in some terrible marriage--in fact, all indications are that it's a pretty good one, and when she tells Lou how much she loves him, she clearly means it. Their banter is playful, their relationship comfy and broken-in. Polley doesn't write Lou as a bad guy, and his occasional insensitivities are also, in their own unfortunate way, bound up in honesty. He's not a villain, he's just a little oblivious.

Nor is Margot perfect. In her first conversation with Daniel, she reveals her neuroses, and Williams doesn't play them as cute (the way a lesser actor would); she seems sweet, but also off-putting and peculiar. But still, something happens between them, something neither of them can deny but both are afraid to act on, and one of the keys to Polley's script is the skill with which she contrasts the routines and rhythms of Margot and Lou's interactions with the electric charge of her flirting with Daniel. They say things they shouldn't, just to see how the other will react, and their thick silences tremble with the eroticism of possibility.

The grass is always greener, of course, and Margot is not unaware that she has a good thing going, that once the scorching attraction melts, who knows how she and Daniel would actually be together. Lou is a known entity, and it may seem inconsistent, the way she can go from dancing up to the edge with Daniel to going back into Lou's bed and sharing their inside jokes. But Polley knows that the intimacy of those exchanges is also bound to short fuses and petty irritations; Margot may fall for the handsome neighbor, but she doesn't fall out of love with her husband, and that is vital to the complexity of the picture. The filmmaker is into the weeds of marriage here, with a subtlety and detail we're not used to seeing in mainstream cinema, and though there may be something to the complaint (already sneaking out in early reviews) that this is a low-stakes situation, the stakes certainly aren't low to these three, and as the film moves into deeper waters--I'm thinking of the Scrambler scene and its aftermath--I found myself regarding Margot's actions with a genuine urgency.

There's not a bad performance in the movie. Williams is the Picasso of cinematic sadness, but she's no one-trick pony; this is one of the most complicated characters she's played, and she nails every single beat. Kirby seizes Daniel's honesty and makes that the key to the character, which is a wise move. Rogen is natural, unaffected, and real--he's just plain good. And Sarah Silverman, well cast as his sister, is given a role that gives her some new and serious beats to play without diffusing what makes her such a pleasurable comic presence.

There is one significant stumble early on, as Margot visits a historic fortress (she's a freelance writer, working on a brochure for the venue) and witnesses a group of re-enactors dramatizing the public lashing of an adulterer. That's foreshadowing so heavy you can sink a ship with it. That happens within the first ten minutes, and Take this Waltz never steps wrong after that--up to and including its final scenes, which are so bittersweet I didn't know what the hell to do with myself. I wept a little. It seemed to work for Margot.

Jason lives in New York. He holds an MA in Cultural Reporting and Criticism from NYU.