Late one morning in Los Angeles, 1947, a gruesome discovery was made. It was a young woman’s body, nude, savagely beaten, mutilated, and bisected. She was later identified as Elizabeth Short, and though her horrific death caused a sensation, no one was ever convicted of the crime. Even now, the Black Dahlia’s murder—so named for Short’s resemblance to an actress in The Blue Dahlia, and her propensity for wearing black—remains perhaps the most sensational unsolved murder in California history.

But Brian De Palma’s The Black Dahlia isn’t really about Elizabeth Short at all. Like the James Ellroy novel it’s based on, it’s far more interested in the constellation of people and desires around her. In many ways it is the classic murder mystery: Unknowing character steps into something straightforward, only to have his illusions and assumptions stripped away as the complexity of the world around him becomes apparent. The crime is merely the catalyst for the true journey.

Our relatively innocent and unknowing protagonist is Bucky Bleichert (Josh Hartnett), a beat cop elevated to Warrants Squad for his boxing skills as much as his work ethic. His partner Lee Blanchard (Aaron Eckhart) is also a boxer, and very much a man’s man. They’re fast friends. Bleichert meets Blanchard’s live-in moll Kay (Scarlett Johansson). For a few blissful months, their lives are perfect. Kay has her “boys,” and Blanchard seems quietly pleased at the growing attraction between Kay and Bleichert. Life could not get better.

Until it gets worse. The cracks show small, at first; ominous whispered warnings to Blanchard about a particular con hitting parole soon. A promise forced on Bleichert not to tell Kay. A shootout with a lowlife pimp that begins unclearly, with no sense of who shot first.

And then Elizabeth Short dies, a mere block from the pair’s stakeout. The assistant DA (Patrick Fischler) wants a big fat headline for the capture of the Dahlia’s killer, and Bleichert and Blanchard—along with over 100 other detectives—are assigned to the case. For Bleichert, the straight and narrow has become twisting and uncertain. Who was Elizabeth Short? What ties does she have to the poisonously seductive daughter (Hilary Swank) of a famous real estate developer, a woman who frequents lesbian night clubs dressed as the Dahlia herself? Who could commit so much savagery on a woman who never left much of an impression on anyone?

It’s an effectively nuanced film, though not quite as deep as the novel. The film teases at what the book explores; namely, the obsessive projection and unhealthy fascination that dead, pretty young women create in their self-appointed, posthumous saviors. In the wake of the John Mark Karr fiasco, this observation seems particularly pointed.

The first trailer for The Black Dahlia is set to Death in Vegas’s “Dirge.” It’s a slow song, mysterious, sad, and sexy. It’s also very modern. The actors—Josh Hartnett, Aaron Eckhart, Hilary Swank, Scarlett Johansson, Mia Kirshner—are relatively young and accomplished. So is The Black Dahlia a slick, contemporary lens on detective noir?

No. Empathically no. The Black Dahlia is set in 1947, and in many of its conceits it is very much a movie of that era. Certainly the sex and the violence are modern, as are the acting styles; the characters are part of their world, rather than interpreters of it. But the sensory details, the actual mechanics of the film, belong to another time. Wipes are used instead of cuts, and the score does a lot more work than modern audiences may be used to.

It works, and the film is stronger for it. It may also be the best work Brian De Palma has done in years. (Depending on who you ask, that may not mean a lot.) Some critics have said Dahlia starts to fall apart in its final reel, and they’re not altogether wrong—what is a string of coincidences, hunches, and roundabout conclusions set over a long period of time must necessarily be compressed for time’s sake in the film. What results is the only clunker scene in an otherwise confident, seductive film. Secrets are revealed—first by one person, and then another appears to make further revelations, until every motive is laid bare. It’s a Parlor Room Revelation scene, only with more bullets.

But the whole product is satisfying. De Palma has created a convincing half-remembered, half-invented world of 1947, and his actors make scene-chewing look completely natural. Its central murder mystery is halfway believable, suffering mostly for its hurried slapdash of motives. But the murder doesn’t matter as much as the people who made it possible. No, The Black Dahlia is not about Elizabeth Short. It’s about the kind of world that would kill her the way it did.