How does a witty, fiendishly clever movie starring Julia Roberts and Clive Owen as corporate spies playing head games on each other fail at the box office?

When "Duplicity" stalled at a $40 million gross earlier this year, the culprit may have been a screenplay so packed with twists and turns it even outfoxed the audience. That shouldn't be as big of a problem on home video, where your trusty rewind button allows you to go back and rewatch scenes of exposition that might leave you a little befuddled.

But the beauty of "Duplicity," the second film from writer-director Tony Gilroy ("Michael Clayton"), is the speed and dexterity with which the complicated story unfolds. The film only seems confusing if you're not paying attention. Gilroy, who also wrote the screenplays of the three "Bourne" pictures, has an unerring sense of pace and plot construction. "Duplicity" is a big Bavarian pretzel of a movie, but one that has been beautifully contorted.

The DVD and Blu-ray versions include only one extra, but it's a great one. Gilroy and his brother John (who served as editor and co-producer) deliver an illuminating and informative commentary track.

It was recorded shortly before the film's release, so they never talk about the disappointing public reception of the movie.

They do, however, go into great, fun detail about the project's history. Gilroy originally wrote "Duplicity" seven years ago for Steven Soderbergh to direct, with the provision that Soderbergh would set the script free instead of sitting on it indefinitely if he decided not to make it.

Once Soderbergh passed, various others circled the project, including Steven Spielberg and David Fincher, but no one fully committed. Halfway during the filming of his first movie, "Michael Clayton," Gilroy decided he'd make "Duplicity" himself, and when "Clayton" star George Clooney introduced him to Owen during a break in shooting, Gilroy found his leading man.

Gilroy says that part of what makes Owen such a good actor is that he's utterly comfortable in his skin, so he's willing to play scenes in which he's emasculated by a female co-star in a battle of wits.

Gilroy also reveals that "Duplicity's" opening scene, which is set in Dubai, was originally written at the request of Spielberg but that it was shot half-heartedly, because Gilroy never really intended to use it. But after test-screening the movie, Gilroy realized the scene was essential, because it made "little explosions of difference" throughout the rest of the film, a testament to Spielberg's uncanny storytelling skills.