The premise of Duplicity, the painful new “comedy” from director Tony Gilroy, is that no one can trust anyone else. The characters never know who’s working for whom, when they’re being played, or, essentially, what the hell is going on. Unfortunately, neither does the audience. For over two hours, we sit in a state of increasing befuddlement, wondering how the A-list cast got roped into doing such a ridiculous movie. (Perhaps Julia Roberts needed the cash to redo her kitchen?)

The plot, or at least the decipherable portion of it, centers on Ray (Owen) and Claire (Roberts), ex-government operatives who team up to con two companies out of $40 million. What follows is a mishmash of businessmen yelling at each other, flashbacks to Ray and Claire’s relationship history, and banter that fails to be witty.

Duplicity’s screenplay is perhaps its weakest feature. The movie is ostensibly a screwball comedy in the Tracy-Hepburn tradition, but Clive Owen is no Spencer Tracy, and Julia Roberts is no Katherine Hepburn. The stars have virtually no chemistry, an impressive feat considering that this is not their first film together (they also co-starred in 2004’s Closer). Roberts is wooden, cracking maybe three smiles in more than two torturous hours, and barely altering her vaguely pissed-off expression. Owen is a little better: he manages to deliver a few decent one-liners, but the material he has to work with is so lacking in charm that even his best lines fall flat.

Not even Paul Giamatti’s solid performance as a company executive is enough to save this movie. Duplicity’s characters may all be trying to pull one over on each other, but it’s everyone who has paid to see this train wreck of a film who have really been duped.

Duplicity .5 stars Directed by: Tony Gilroy Starring: Julia Roberts, Clive Owen, Paul Giamatti Rated: PG-13, 125 min.