Silver Screen: No Strings Attached ***

A romance pairing Harvard grad Natalie Portman and enthusiastic, empty-eyed camera pitchman Ashton Kutcher sounds like the intellectual equivalent of Beauty and the Beast-- he's hated and feared by a society that can't see beyond an I.Q. that looks like an incomplete Pick Three lottery number!-- and yet the frothy rom-com No Strings Attached is surprisingly amiable.

Kutcher and Portman costar as childhood summer-camp friends Adam and Emma, who reconnect briefly in college, then again later in life when he is somewhat implausibly attempting to be a writer while she (much more plausibly) works long hours as a doctor. They're casual pals until one night Adam goes on a drunken bender after discovering his self-obsessed father (Kevin Kline), an aging actor, starts dating his ex-girlfriend. Emma's consolation turns into an unexpected hookup, one that gives the emotionally repressed physician an idea: She and Adam should have sex and spend time together but not integrate any elements of romance into their relationship to avoid hurting one another.

It's inevitable, of course, that this friends-with-benefits accord will lead to the two developing feelings for one another, and the ensuing comedy of errors will result in one of them running/driving quickly to an airport/train station/office building to make a protracted declaration of love. No Strings Attached rarely deviates from the standard constructs of its genre, right down to the jovially supportive friends for him (Jake Johnson and Ludacris), neurotic cohorts for her (indie queen Greta Gerwig and The Office's Mindy Kaling), and pop-music montages. But director Ivan Reitman, working off a script from Elizabeth Meriwether and Michael Samonek, plays nicely within the formula.

It would be absurd to label the movie realistic-- writer Adam spends approximately zero time writing and appears to do fairly little actual work at his job on the set of a High School Musical-style TV show, while Emma and her doctor pals seem to always have lots of time for lunches together and roommate-bonding time without any of the attendant stress of trying to heal the sick and dying and whatnot. But this does count as realistic for Reitman, whose most prominent works involve the supernatural (Ghostbusters), the extraterrestrial (Evolution), the superheroic (My Super Ex-Girlfriend), and the Schwarzenegger (Kindergarten Cop). But No Strings Attached not only lacks a gimmick, it's almost plotless, consisting almost entirely of quiet moments and appealing banter, occasionally implausible but always character-driven.

Kutcher is surprisingly low-key and almost slightly plausible as a writer-- as Adam himself puts it, the show he wants to write for is "mostly just kids singing about homework"-- and he's more charming here than overwhelmingly goofy. He has decent chemistry with Portman, whose performance is an astounding 180-degree turn from her portrayal of a mentally unraveled ballet dancer in Black Swan. The Portman of Black Swan is bony, tremulous, and impossible to imagine laughing, much less telling a joke, but here she channels an easygoing grace and ace comic timing. The supporting players are likeable too, even if Reitman doesn't seem to know what to do with them, and the lovely Gerwig is almost too wonderful not to be starring in a romantic comedy of her own. Only the awkward subplot with the otherwise excellent Kline is distracting and ultimately used to force some plot machinations, but the movie is easygoing enough to forgive its minor flaws, willfully inconsequential but thoroughly enjoyable.