As formulaic as buddy cop movies tend to be, they're also unpredictable in a fundamental way: It's hard to know beforehand who the true dream teams are going to be. Mel Gibson and Danny Glover? We know now that they're franchise material, sure, but who knew going into the first ''Lethal Weapon''? The same could be said for Jackie Chan and Chris Tucker in ''Rush Hour'' or Nick Nolte and a young Eddie Murphy in ''48 Hrs. ''
That said, partnering Murphy with Robert De Niro for the TV-cops comedy ''Showtime'' would seem to be surefire casting. The catch is that they're stuck with a script that prevents them from firing on all cylinders.
De Niro's veteran LAPD detective, Mitch Preston, is a RoboCop without the circuitry, dourly sworn to protect and serve and not get fancy about it. Murphy's Trey Sellars, meanwhile, is a unique brand of Hollywood hyphenate: beat cop-actor, hustling to auditions on his lunch hour. Sparks fly when Trey fouls up an undercover drug bust that Mitch is orchestrating. Mitch, fuming, fires a shot at a news camera covering the fiasco, and in a make-good public relations move designed to keep the news crew's bosses from suing, he's (naturally) ordered to play the lead cop in a new reality TV show being produced by industry slickster Chase Renzi (Rene Russo).
Wannabe Trey gets wind of the project, of course, and in one of the movie's better bits, he stages an elaborate purse-snatching-and-apprehension drama to convince Chase to put him in the show, too. Cut to plenty of Mitch-Trey verbal sparring, a series of escalating run-ins with some drug-dealing nasties with unbelievably loud guns, and, of course, the chase.
At a point in Murphy's career when it seems like all his hits are gimmick-driven - the prosthetics of ''The Nutty Professor,'' the computer-generated cuteness of ''Dr. Dolittle'' and ''Shrek'' - his return to wisecracking-detective turf feels fresher than one might expect. In some ways, this might have made a worthier ''Beverly Hills Cop'' follow-up than the sequels Murphy actually did make. De Niro, meanwhile, is also game, but in setting him up as a stiff, the movie simply doesn't give him enough opportunity to be anything but stiff.
De Niro and Murphy are at their best when they're at each other's throats. The movie's occasional cursory attempts at more sincere moments between them, when genuine bonding is supposed to be going on, aren't nearly as effective. If anything, the film's best interplay is between them and William Shatner, who plays himself in a terrific cameo as the show's acting coach. (The film also boasts an even wackier, only-in-Los Angeles cameo that we won't spoil here.) Shatner might be giving Leslie Nielsen a little too much competition in the parody-hack-for-hire department these days, but you can't fault him for taking this role. If only all the TV cops in ''Showtime'' were allowed to have this much fun.