The actors have signed on to star in New Line Cinema's "Apaloosa," based on the acclaimed novel by Robert B. Parker, repors Variety.
Harris will be wearing multiple hats for the film beyond the traditional Stetson. He'll climb into the director's chair after co-writing the screenplay with Robert Knott. Both men will also produce.
Two pals and Old West lawmen (Harris, Mortensen) team up in the mining/ranching town of Appaloosa to take on a corrupt rancher who had the previous marshal and deputy killed. After he's arrested and sentenced to be hung, he's busted out of jail and is on the loose, only to later meet up with the lawmen for the classic showdown. Along the way, a malevolent, attractive widow distracts one of them, leading to a final confrontation.
Shooting will begin on Oct. 1 in New Mexico.
Harris previously directed himself in "Pollock." He'll be seen next in "Gone Baby Gone," "The Cleaner" and "National Treasure: Book of Secrets."
Mortensen of "Lord of the Rings" fame next stars opposite Naomi Watts in the crime thriller "Eastern Promises," due for release on Sept. 14.
Zellweger can next be heard in "Bee Movie," opening nationwide on Nov. 2. She'll also star in the upcoming George Clooney vehicle "Leatherheads" and the thriller "Case 39," both of which will be released in the winter.