It’s easier to admire “Wicker Park” for what it DOESN’T do than what it does do.

Despite ads that make this movie look like “Single White Female” or “Fatal Attraction,” the story isn’t about homicidal roommates or malevolent affairs. Admirably, this is the rare thriller that avoids a body count.

Josh Hartnett plays a man who believes he sees his ex-girlfriend (Diane Kruger) suddenly reappear after mysteriously vanishing in the romantic thriller, Wicker

Instead, “Wicker Park” concerns people whose love borders on obsession, and what deceptive lengths they will go to in order to protect it.

Based on “L’Appartement,” a 1996 French film (or what the Bush administration would call a “Freedom film”), the story centers on an advertising hotshot named Matthew (Josh Hartnett). After a two-year stint in New York, Matthew returns to Chicago with a fiancee in tow.

On the brink of a big business deal for which he must travel to China, Matthew thinks he spots his old flame Lisa (Diane Kruger). Prior to his New York move, Matthew had a passionate affair with the beautiful ballet dancer and eventually asked her to move in with him. Then Lisa vanished without a word, apparently heading back to Europe.

Aided by his friend Luke (Matthew Lillard) — who is having relationship troubles of his own — he attempts to piece together a seemingly arbitrary assortment of clues as to Lisa’s mysterious disappearance and whether she has returned to the Windy City.

At this point the plot becomes so twisty that it’s best not to explain much more. But suffice to say that the flashback-heavy story comes together in an unexpected manner. And key events are replayed from different viewpoints that give matters new perspective.

Wicker Park 1/2 Find showtimes, trailers and more on the movie

Scottish director Paul McGuigan attempts a distinctive visual style, and sometimes he borders on overkill. Seeking to punctuate the duality of his characters, the filmmaker exploits every available tool to allow his actors to cast a reflection. They’re constantly framed next to mirrors, windows, water, etc.

(Alfred Hitchcock employed this technique all throughout “Psycho” with a much subtler hand.)

McGuigan also relies on editing tricks, such as split screens, with better results. Occasionally, he even sneaks in this “double identity” in less noisy ways. There’s a running gag about drivers taking other people’s parking spaces — although it sure seems easy for Hartnett to find available spots in downtown Chicago.

Writers Gilles Mimouni and Brandon Boyce craft an intricate script that holds together even when the movie relies on dubious coincidences. (What is that dangling subplot involving the married widower?) Their fresh narrative helps overcome some of the potholes in the casting.

It doesn’t help that the supporting characters played by Lillard and Rose Byrne are much more vivid than the comelier leads. Nor that the actors portraying them have scads more cinematic charisma.

“Don’t take this the wrong way, but I just think you’re a nice guy,” Byrne tells Hartnett. In certain respects that’s how Hartnett comes across on camera. He seems like a clean-cut, friendly dude. But he has no more command of the screen than the dozens of other generic leading men in his generation, from Paul Walker to Chris Klein.

Beyond the performances, “Wicker Park” also suffers from a lack of momentum. It takes a good hour before the first of many plot twists rises to the surface. Prior to that mark, the picture feels like it’s just spinning on its axis — all atmosphere and no drama.

This section relies on the gravitas of the central relationship to carry the story. Yet Hartnett and Kruger’s characters feel mismatched. He’s a yuppie frat guy, and she’s a European artiste. They may LOOK like a couple; their personalities speak to the contrary.

Therein lies the main aspect preventing “Wicker Park” from capitalizing on its numerous virtues: ambitious script, slick director, strong supporting cast … wrong lead actors.