TORONTO - "Appaloosa," a tale about two hired guns (Viggo Mortensen and Ed Harris) who clean up an Old West town, is an ode to Hollywood's great westerns -- yet it's something completely different.

"It's so well written, especially for a western. Most aren't. They're terrible," Mortensen told reporters at the Toronto International Film Festival.

Based on the book by Robert B. Parker, director Harris and Robert Knott crafted the screenplay for this complex saga about two long-time gunmen and friends who ride into a dangerous New Mexico town. Ruled by a merciless rancher (Jeremy Irons) and his trigger-happy hoodlums, the good guys decide it's time to clean things up before any more bodies litter the streets of this dust bowl.

Of course, the idea of social "good" being enforced by men who pack pistols presents a moral quandary. But survival rather than soul searching also rings true to "Appaloosa's" time period.

"Being a law man was the best way of being a gun man. You got paid," says Harris, who masterfully brings to life all the sun-baked anarchy and tight-laced social conventions of the day.

"It's very clear in this movie that this is no place for women. Hell, it's no place for civilized men," says Harris. "Where's a woman supposed to fit in all that?"

The arrival of a mysterious young widow (Zellweger) answers that question in ways that are wondrously complicated, instead of the usual Western clich�.

Zellweger shoots to win

Unlike the two-dimensional schoolmarms or saloon prostitutes Hollywood has long served up "Allison French" runs the show according to her own mysterious agenda.

"Here's a woman who has questionable moral parameters. Even after I read the book she was a complete mystery to me," says Zellweger, who leaves that famed "Bridget Jones" effervescence in dust for this challenge.

"I found Renee's character very direct for that time. She's very brave to have gone out there on her own," says Mortensen.

"Frankly I couldn't judge this woman," says Zellweger. "When she's asked if there's a Mr. French you never really know. All the while I kept waiting for things to reveal themselves about her. I've never had that experience before."

In the end Zellweger delivers a performance that's as steely and well aimed as Wyatt Earp's Winchester.

"It required very little consideration for me to sign on," says Zellweger. "The experience was intense, the environment was challenging and the costumes were gorgeous. Seeing these guys in chaps and riding on horses every day didn't hurt."