Why did De Niro, Pacino sign on to do 'Righteous Kill'?

Robert De Niro and Al Pacino probably still have enough fans to get respectable box-office numbers for the opening weekend of "Righteous Kill." But very soon, their fans will speak of their poorly thought-out pairing in this halfhearted cop thriller in hushed tones, as though their idols were ill when they agreed to make it and are still recuperating.

The two screen icons surely weren't thinking clearly when they signed on to play New York police detectives trying to catch a serial killer. First off, the script is a mess. And second, well, doesn't the NYPD insist on retiring cops once they've served 30 or 40 years? Isn't 65 (or older) pushing it?

Granted, movies call for a suspension of disbelief, but there are limits. It looks as though director Jon Avnet went out and hired Brian Dennehy to play De Niro and Pacino's boss so they'd look young by comparison, except that the trick doesn't actually work.

Even if the movie were better, the age thing would matter. Especially when it gets to the creepy sexual relationship between Turk (De Niro) and Karen (Carla Gugino), the forensics expert who seems to be making her way through the male roster at her precinct.

But hey, how about that plot? And those nicknames? Turk and partner Rooster (Pacino) -- who keep their eye on a drug dealer called Spider (Curtis "50 Cent" Jackson) -- notice a pattern with some murders. All of the victims were scumbags who managed to evade jail, and each one has a brief poem left next to his body.

Working reluctantly with younger detectives Perez (John Leguizamo) and Riley (Donnie Wahlberg), Turk and Rooster are bothered by the implication that a cop may be the killer.

Written by Russell Gewirtz ("Inside Man"), "Righteous Kill" spends most of its length toying with a gimmick that's not nearly as clever as the filmmakers think it is. Style trumps substance and forces a late-hour reveal that emphasizes how much of the film is tell, not show.

Looking for something that extends their legacy beyond shared billing in "The Godfather II" and the flip-side protagonists of "Heat," De Niro and Pacino find themselves in a formulaic police thriller that lets them emote but not act. They have the beginnings of a nice spoof of themselves.

Effectively shot by Denis Lenoir, the film is packed with corpses and tough talk but not a lot of action. "Righteous Kill" loses its uphill battle to be relevant.

Rated R for violence, pervasive language, some sexuality and brief drug use.

2 stars (out of five).

(Contact Knoxville News Sentinel film critic Betsy Pickle at pickle(at)knews.com.)