About an hour into Robert Rodriguez's new film "Once Upon a Time in Mexico" I realized that I had absolutely no idea what was going on. Plots, counterplots, counter-counterplots, intricate cross-cutting from one to another, plus flashbacks, made it impossible for my sluggish brain to follow. Had it not been for Johnny Depp holding the screen together, the movie would have flown to bits before our eyes.

"Once Upon a Time in Mexico" is the last, I think, or at any rate the latest, in the series that began with "El Mariachi," Rodriguez's 1992 film about an assassin who works as a mariachi musician and carries his weapons inside his guitar case. He followed that with "Desperado," in 1994, where Antonio Banderas took over the role; and Banderas returns here as well. This time he has so little to do that we suspect Rodriguez only had him available for a few days of shooting. But the story is such a mess that had he been available for months I doubt it would have made much difference.

Rodriguez is the last of the full-tilt filmmakers working these days. He not only wrote and directed the movie, he also shot it, edited it, and wrote the music as well. This is both a good and a bad thing. He is enormously talented at each of those fields, but here at least he needed to test his ideas against someone else - anyone else - in order to focus his film more coherently.

The real star of the film, and this seems to be his summer for flamboyance, is Depp. He is a rogue CIA agent, stationed in Mexico. He wears t-shirts that are the most delicious things in the film; his first one is emblazoned with 'CIA' on it; another points down and says 'I'm with stupid'; and a third says 'Yo Quiero Taco Bell,' and since another character carries a pet chihuahua we have a point of reference. He also wears a third, prosthetic arm (don't ask), and shoots when, and whom, he wishes. I love him.