In ''Once Upon a Time in Mexico'' (Sept. 12), a sequel of sorts to 1995's ''Desperado,'' Johnny Depp plays a sociopathic CIA agent who hires Antonio Banderas' El Mariachi to sabotage a political assassination on the Day of the Dead. Not surprisingly, Depp -- known for the quirky qualities he's brought to such films as ''Edward Scissorhands,'' ''Ed Wood,'' and ''Fear and Loathing in Las Vegas'' -- had certain ideas about his ''Mexico'' character. ''Before he even got there he called and said, 'I imagine this guy wears these really cheesy tourist shirts,''' recalls director Robert Rodriguez, who admits that he still had no idea what he would be in for.
Before showing up on the set in San Miguel de Allende, Mexico, Depp called his sister in Florida and had her scour the area for T-shirts with silly slogans like ''CIA: Cleavage Inspection Agency'' and ''I'm With Stupid,'' featuring an arrow pointing below the belt. ''Florida has no shortage of idiotic T-shirts,'' says Depp. ''I was also desperately looking for one of those baseball caps that say ''S---head'' and has a picture of a coil of dookie on the bill.'' Some of Depp's other flourishes for his character included carrying around a Judy Garland biography (''I just kind of figured that this guy might have a sideline obsession with Broadway'') and wearing an assortment of obvious disguises (''That's why I brought along all my wigs and fake mustaches'').