Screened at Toronto. "It's 1948 and postwar Los Angeles is booming, but Easy Rawlins has seen better days," begin this film's press notes, yet the black PI made famous by Walter Mosley's mysteries sees great days on the big screen in "Devil in a Blue Dress." In this smashing adaptation by writer/director Carl Franklin ("One False Move"), Easy finds himself accidentally em-broiled in city hall secrets, murder and illicit love. The way out for Easy is his way in: a mixed-race young woman named Daphne (Jennifer Beals) who has been targeted by a mayoral candidate with something to hide.
   Although the novel's Easy-Daphne romance has been oddly excised, the look of that era's L.A. has been marvelously recreated by Franklin, cinematographer Tak Fujimoto and production designer Gary Frutkoff, and that's one of the film's two highlights. The other is Washington, who has an appealing easy way about him, nicely moving his character from uncertainty to intentness. In a supporting role as his close-to-crazy former partner from down south, Don Cheadle comically yet dangerously energizes every scene he's in. The question is not whether the movie will succeed, but whether its success will give TriStar a new film franchise. Starring Denzel Washington, Jennifer Beals, Tom Sizemore and Don Cheadle. Directed by Carl Franklin. Produced by Gary Goetzman and Jesse Beaton. A TriStar release. Mystery. Rated R for violence, sexuality and language. Running time: 105 min