“The Black Dahlia” is one of the worst films of the year.

Given its potential, with an all-star cast and big name director, it’s certainly the most disappointing. The film teams director Brian De Palma (“Scarface,” “The Untouchables”) with author James Ellroy (“L.A. Confidential,” “Dark Blue”), a noir match that would seem perfect. Both have a knack for delving into underworld crime and etching out vivid characters.

How the people who brought “Officer Bud White” and “Tony Montana” made a movie as bad as “The Black Dahlia” is confusing.

Not that it’s important, but here is the plot. Detectives Lee Blanchard (Aaron Eckhart) and Bucky Bleichert (Josh Hartnett), after competing in an amateur boxing match with each other, become great friends and eventually partners. Bucky even moves in with Lee and his girlfriend, Kay Lake (Scarlett Johansson).

Any moviegoer can see where that triangle leads. The two get assigned the Elizabeth Short (Mia Kirshner) murder case, nicknamed “Black Dahlia” because she was known to wear black clothes. As Bucky chases down leads, Blanchard becomes obsessed with Short, and in the process jeopardizes his relationship with Kay.

De Palma hints toward suspicious elements from Short’s past that might have something to do with her murder. Everything from a former lesbian lover to Mickey Cohen is a suspect. Bucky’s investigation of Short leads him to her ex-girlfriend, Madeleine Linscott (Hilary Swank), Linscott’s film producer father’s mansion in Beverly Hills, a porn studio just outside L.A. and a lesbian night club. He also discovers his partner may have known more about Short than he is letting on.

None of these side stories are interesting or provide any evidence into what happened to Short.

By the preposterous ending, De Palma has lead us in so many red herring-type directions we no longer care who the real killer is. He spends too much time on relationships between meaningless characters to make the murder mystery actually mysterious. Plus Ellroy’s story has absolutely no factual basis. It’s completely made up. There is no mention of Lt. Joseph Gordon, Short’s on-again-off-again boyfriend. There is no mention of Robert Manley, the man last seen with Short who had been brought in to testify in court about their relationship. And there is inexplicably no mention of Daniel Voorhees, who confessed to the murder to police.

The bright spots are few and far between. Swank is good as Linscott, Bucky’s sultry bisexual lover with big connections and bigger secrets. Chad Lowe has got to be kicking himself for letting her go.

Kirshner does a nice job of showing the inner turmoil and guilt that Short experiences as she gets used and abused during casting sessions.

Johansson is perfect, and her acting is pretty good too, like she’s Marilyn Monroe’s long lost granddaughter. She’s got the voluptuous blonde femme fatale role down. The problem is there’s more chemistry between Bobby Knight and a referee than there is between Johansson and Hartnett. That is strange because reportedly Johansson has moved in with Hartnett.

After seeing them together here, bet on that relationship lasting another week or two at most, which is probably a week or two longer than this movie should be in theaters.

At least 10 people walked out of the theater with 20 minutes left, proving they didn’t care how the story turned out.

I’m sure other viewers were jealous of those who got to leave early.

Paul Giuntoli is a film critic for the Northern Star.