Director Robert Rodriguez returns to the characters of his breakthrough hits El Mariachi and Desperado in this grand scale south-of-the-border action-adventure saga. Sands (Johnny Depp) is a rogue CIA agent who is working in cahoots with Mexican officials who've caught wind of a plan by corrupt military leader General Marquez (Gerardo Vigil) and ruthless drug kingpin Barillo (Willem Dafoe) to assassinate Mexico's president (Pedro Armendáriz Jr.). Sands needs to recruit a gunman to take out Barillo's assassins before they can complete their mission, and through barman Belini (Cheech Marin), Sands learns of El Mariachi (Antonio Banderas), a fabled musician turned vigilante with a remarkable talent for violence, and a score to settle with Marquez. El Mariachi is living quietly in hiding after the death of the woman he loved, Carolina (Salma Hayek), but Sands lures him back into action through the promise of a final showdown with his nemesis Marquez, forcing El Mariachi to retrieve his guitar case (containing a mighty arsenal) and once again do battle against the lawless. Robert Rodriguez not only directed Once Upon a Time in Mexico, but he wrote the screenplay, handled the camera work, edited the film, and composed the musical score.
by Mark Deming synopsis