Whatever you choose to call the quality that allows for the suspension of disbelief, that clears the way for acceptance and potential approbation, The Black Dahlia doesn't have it. Adapted from James Ellroy's novel about the unsolved 1947 murder of aspiring actress Elizabeth Short, the picture fails to hook early on, so you resist being taken where it wants to go, no matter how intriguing that destination may be.

The gruesome material is ideal fodder for Brian De Palma, a director who has never shied away from the intersection of sleaze and mayhem. Ellroy's take on the crime is also right up De Palma's alley. The sordid case--involving a loose young woman whose body was dismembered and disemboweled--is tailor-made for both sensibilities. It contains salacious themes that De Palma and Ellroy have treated in the past, with more success.

One posivite feature of The Black Dahlia is that it offers a solution to the murder. It may be pure fiction, and following some of the crucial details may not be easy, yet at least the diffuse narrative isn't a cop out. The reasons for its inability to convince are manifold and partly related to the diffuse plot.

Josh Hartnett and Aaron Eckhart portray LAPD detectives Bucky Bleichert and Lee Blanchard linked by their boxing prowess, a former prostitute (Scarlett Johansson), and Elizabeth Short's death. The senior officer Blanchard, known as Mr. Fire in the ring, is obsessed with rescuing women from bad men, while Hartnett's greener, less hot-headed Bucky (Mr. Ice) is feeling is way through the department and the world. Their similarity to the cops in Ellroy's book L.A. Confidential is enticingly superficial and hence disappointing.

Too much time is spent here on their triangular relationship with Johansson's fallen femme (a knock-off of the L.A. Confidential dame Kim Basinger won her Oscar playing) as they join an elite squad that investigates the Dahlia murder. This imbalance is indicative of De Palma's attempt to combine the stuff of a noir thriller and an hysterical melodrama; his tone quavers between steely horror and psycho-sexual delirium. The movie can appear feckless when you're not being harangued by obvious music and a significant number of shots possibly lifted from a noir cinematography manual. 

A lack of style commitment is reflected in the often pedestrian staging, especially during the early scenes, and in the forced rhythm. De Palma rushes when he should slow down and adopts a leisurely pace during expositional scenes. Maybe this contributed to the self-conscious acting by Johansson (never give her a cigarette holder as a prop), Eckhart, and Hilary Swank as the ludicrously lock-jawed and predatory Madeleine Linscott, whom Bucky suspects in the murder (along with her wealthy father) but has no problem sleeping with. Hartnett acquits himself fairly well, using a taciturn demeanor to indicate his character is none too bright and perhaps hide his own confusion and discomfort.

And still -- despite all these drawbacks -- the salaciously bizarre yarn never loses your interest completely, much the same way Bucky becomes entangled in webs spun by Kay and Madeleine. You're curious to see where De Palma will take you and it's not routine. Consider, for example, a sequence in which k.d. lang plays a torch singer in a Sapphic floor show and Fiona Shaw's dinner table spiel as Madeleine's psychotically soused mother.

Comparisons with Hollywoodland (released last week), Chinatown and L.A. Confidential -- three better movies concerning the same milieu -- are unavoidable. Notwithstanding the chilling integration of the silent film The Man Who Laughs and affecting snippets of screen tests and skin flicks Elizabeth made, De Palma isn't interested in "the flickers" or in Hollywood's underbelly for its own sake.

Elizabeth Short doesn't represent dashed showbiz dreams as much as deeper foibles (or perversions) that De Palma fails to present with aesthetic unity. The question he poses in The Black Dahlia is whether Bucky is more gallant or voyeuristic. The answer is decidedly the latter, so De Palma, his protagonist, and the viewer emerge as lascivious knaves rather than flawed knights. 

(Released by Universal Pictures and rated "R" for strong violence, some grisly images, sexual content and language.)