There's a line of dialogue in "GRIDLOCK'd" that resonates beyond what the filmmakers intended, when Tupac Shakur says, "Lately, I've been feelin' that my luck's runnin' out."

Shakur, of course, died late last year, the victim of a shooting in Las Vegas (after finishing another movie that is yet to come, titled "Gang Related"). And fans who see his shaded, thoughtful, multidimensional performance here will be all the more saddened to realize that he was developing into quite a fine young actor.

Tim Roth also delivers a terrific performance in this rowdy, profane and very dark comedy about a pair of down-and-out jazz musicians trying desperately to get into rehab during one long day on the streets of Detroit but finding themselves stalled by bureaucratic red tape.

Spoon (Shakur) is younger than his pal Stretch (Roth), but he's more mature, providing a tempered voice of reason that puts the plot into gear when he suggests they kick their longtime drug habits as a New Year's resolution. Stretch, the wild card of this less-than-dynamic duo, isn't sure he can handle it, but he reluctantly agrees to give it a try.

What prompts this desire for change is a horrifying wakeup call, which opens the film and sets the dark comic tone in motion.

It's New Year's Eve, and Cookie (Thandie Newton, who is also excellent), the vocalist of their small-time jazz trio, has slipped into a coma after overdosing on cocaine. Panicked, Spoon and Stretch try to get her to a nearby hospital emergency room.

But elusive cabs, fearful passersby and no-show ambulances conspire to keep them from their task, and ultimately they simply carry Cookie several blocks to the hospital.

In the emergency room, Spoon and Stretch have their first unpleasant encounter with "the system," where a snippy receptionist (Elizabeth Pena, hilarious in an unbilled role) gives them a hard time. And in flashbacks we are shown the relationship between Spoon, Stretch and Cookie and the events leading up to her overdose.

When they hit the streets the next morning to apply for rehab, Spoon and Stretch find themselves being sent from office to office all over the downtown area, hitting one closed door after another. And before the day is over, they'll find themselves on the run as they are charged with the murder of one of their drug-dealing buddies.

Actor Vondie Curtis Hall (TV's "Chicago Hope") makes an impressive writing-directing debut with "GRIDLOCK'd," which is sort of an American take on "Train-spotting," and his confidence is especially strong with the actors. (Shakur and Roth have great chemistry.)

He's also come up with some memorable scenes, as when Stretch tries to fit in with his black friends by using a racial slur as a term of endearment. An ill-advised gesture at best.

Hall doesn't gloss over the harrowing side of addiction, however, as when Spoon and Stretch are horrified to find a friend murdered but even more concerned about where the dead friend stashed his drugs.

The film does occasionally lapse into silly slapstick and caricature, but most of the way this is a tough, funny and scary cautionary tale.

"GRIDLOCK'd" is rated R for graphic violence, constant profanity, racial slurs, vulgarity, nudity and drug abuse.