Bill Murray as a tough mobster? Robert De Niro as a mild-mannered Chicago cop? Who cast this thing, anyway?

Surprisingly, the casting works. Both actors are good in their roles, and it helps that Murray plays a mobster with standup comedy aspirations.

But the film itself lets them down, with shifts in tone that are too stark, scenes that are too dark, sex that is too explicit and a violent fist-fight showdown that becomes more of a letdown.

Still, if you're a dyed-in-the-wool Murray or De Niro fan, "Mad Dog and Glory" may have enough curiosity value to be worth a look.

"Mad Dog and Glory" has been on the shelf for a while and it's hard not to think Universal Pictures finally released it to cash in on Murray's "Groundhog Day" success. That may give it a boost in its first week or two but in the long haul this one is bound to be a box office disappointment.

De Niro plays "Mad Dog," an ironic nickname since he is really as meek a cop as the screen has given us in some time. He's an "evidence technician," shooting photographs at crime scenes and analyzing what he finds.

One night, he goes into a minimart and finds a robbery in progress. The thief is behind the counter, a gun in his hand and his foot on the head of a customer. What he obviously doesn't know is that his victim is a tough hood named Frank Milo (Murray).

Mad Dog talks the thief into leaving the store, saving Frank's life in the process. But before he knows it Frank is also gone. Then, like the virtual bad penny he is, Frank comes back into Mad Dog's life and won't let him alone. On the advice of his psychiatrist, Frank is determined to repay him in some way.

One morning, Mad Dog's "gift" arrives — Glory (Uma Thurman), a young woman who is in Frank's debt. She belongs to Mad Dog for a week, but Mad Dog, the ultimate straight-arrow cop, is appalled. Until Glory manages to convince him that if he doesn't keep her for a week, Frank will think she has failed in her assignment — and it won't be pleasant for her.

You can probably guess the rest: Mad Dog falls in love with Glory and when the week is over he doesn't want to give her up. Frank, however, is not one to take rejection lightly.

"Mad Dog and Glory" is a curious film, one that goes for light comedy one minute then harsh violence the next. There are also a couple of rather explicit sex scenes and some angry, tense moments, followed by tender or comic ones.

This is a very uneasy mix, one that shifts the tone so often and to such extremes that it merely amplifies the film's weaknesses. And that's too bad, since the characters have potential for being quite appealing.

The only one that is truly appealing, however, is De Niro's. His performance is a real highlight here.

Thurman and Murray manage to be interesting, but Kathy Baker, a fine actress (currently in TV's "Picket Fences"), is saddled with a thankless role as De Niro's former girlfriend, who lives across the hall.

"Mad Dog and Glory" is rated R for violence, sex, nudity, profanity and vulgarity.