If you heard just the intense musical score of Ruby Sparks, you probably would think it was about spies shooting at one another. If you watched only the images, you would think it's about the kind of lovers who have picnics and shampoo each other's hair. That disconnect is our first clue that there's more to the movie than meets the eye/ear.

Paul Dano, who seems to be channeling Woody Allen — and not just because he favors well-cut Ralph Lauren sportswear — plays Calvin, a novelist who dreams up the title character (Zoe Kazan, Dano's real-life partner). He wrote her, so she's exactly the woman he thinks he wants. For a while.

Eventually, Ruby grows tired of being a male fantasy figure, and Calvin realizes a real thinks-for-herself woman is more interesting than what Calvin's brother calls "quirky girls whose problems make them endearing" (i.e., virtually every female co-star of every Will Ferrell or Jim Carrey comedy).

Screenwriter/actress Kazan's theory seems to have been that if she's going to write herself a part, she might as well make it a crackerjack one. Kazan must turn on an emotional dime — sometimes Ruby is acting out the stuff Calvin imagines while he is writing and rewriting it — and her dazzling performance is comparable to an orchestral piece composed of variations on a musical theme. Essentially, Ruby Sparks makes fun of every manic, pixie dream girl ever played by Zooey Deschanel, whom Kazan resembles, but there's not an ounce of meanness in Kazan's funny, earthy acting.

Her writing is not always as sharp. The supporting characters are played by fine actors (Annette Bening, Antonio Banderas, Chris Messina), but their roles are all fairly cartoonish. And some details seem to have been included for convenience rather than because they make storytelling sense: Calvin's therapist vanishes from the movie, for instance, at the exact moment we know Calvin would be reaching out to him. And why does the pleasant, successful Calvin have no friends?

But those are the kinds of lapses first-time screenwriters like Kazan can fix in subsequent efforts. Now, the only question is which is more exciting: The prospect of more screenplays from the gifted Kazan or more big movie roles?