A romantic vacation hiking the wilds of Hawaii is not in the cards for one couple in the somewhat engrossing thriller A Perfect Getaway. Since there are three couples on that trail, the trick to this not-as-tricky-as-you'd-hope mystery is figuring out which couples are potential victims and which are murderers.

It has only one conventionally tricky way the mystery can resolve itself. That doesn't mean the finale of this David Twohy (Pitch Black) film isn't a lulu.

Cliff and Cydney ( Steve Zahn and Milla Jovovich) are newlyweds spending their honeymoon trekking on Kauai. He's fresh out of film school, a "screenplay writer" she crows.

"Actually, we're called screenwriters," he corrects.

The people they meet aren't exactly charming company. There's the rough-hewn Kale and Cleo (Chris Hemsworth and Marley Shelton), scary hitchhikers who take an instant dislike to them. Trail-mates Nick and Gina (Timothy Olyphant and Kiele Sanchez) are chatty free spirits. But Nick's got a million stories about his violent "Special Forces" past, tips for Cliff's script's "second-act surprise" or "red snapper."

"Red herring," Cliff corrects.

"You're a screenwriter, I'm a Jedi," Nick cracks back.

Olyphant (Hitman) is making a nice career for himself out of his spooky eyes and bad-guy vibe. He has lots of fun with Nick, all swagger and bluff, a regular Man vs. Wild.

"He is really hard to kill," drawls Gina at a death-defying tale from Nick.

But out there in the Hawaiian boondocks, word creeps in about murders in Honolulu, and Cliff and Cydney start to panic.

Jovovich, who has morphed from skinny model into the resident butt-kicker of the Resident Evil movies, gives Cydney girlish touches, playing naive to the hilt.

It's too bad Twohy relied on that student screenwriter's crutch -- a screenwriter character in a movie about thriller cliches -- and typed himself into a corner. The exotic setting and characters deserve more riveting situations than this imperfect Getaway gives them.

A Perfect Getaway Three of five stars Cast: Milla Jovovich, Steve Zahn, Timothy Olyphant, Kiele Sanchez Director: David Twohy Running time: 1 hour 35 minutes Industry rating: R, graphic violence, language including sexual references and some drug use.