The story follows the adventures of El Mariachi (played by Antonio Banderas), a legendary guitar-playing gunslinger seeking revenge for the death of his wife and daughter. He is recruited by CIA agent Sheldon Sands (played by Johnny Depp) to stop a coup d’état in Mexico orchestrated by a corrupt military general, Marquez (played by Gerardo Vigil), and a powerful drug lord, Barillo (played by Willem Dafoe).
As El Mariachi embarks on his mission, he reunites with his former lover, Carolina (played by Salma Hayek), who is now married to a local bookstore owner. Despite their complicated history, Carolina agrees to help El Mariachi in his quest for justice.
Meanwhile, Sands manipulates various factions in Mexico, including corrupt government officials and rival drug cartels, to further his own agenda and eliminate his enemies. Sands also enlists the help of retired FBI agent Jorge Ramirez (played by Rubén Blades) and a group of Mexican revolutionaries led by Ajedrez (played by Eva Mendes).
As the coup d’état unfolds, El Mariachi finds himself caught in the middle of a deadly conspiracy involving betrayal, deception, and revenge. He must use all of his skills and resourcefulness to outwit his enemies and prevent a massacre.
In the climax of the film, El Mariachi confronts Marquez and Barillo in a final showdown, leading to a violent and explosive confrontation. With the help of Sands and his allies, El Mariachi emerges victorious, avenging the deaths of his loved ones and restoring peace to Mexico.
In the end, El Mariachi rides off into the sunset, leaving behind a legacy of heroism and courage. Although he has lost much along the way, he finds solace in knowing that justice has been served and that he has made a difference in the world.
“Once Upon a Time in Mexico” is a stylish and action-packed film that combines elements of westerns, spy thrillers, and revenge dramas. With its dynamic performances, kinetic action sequences, and intricate plot, the movie offers an exhilarating and satisfying conclusion to the “Mexico Trilogy.”