CLEAN AND SOBER - * * * - 1/2 Michael Keaton, Kathy Baker, Morgan Freeman; rated R (violence, sex, nudity, profanity, vulgarity, drugs); Cineplex Odeon Family Center Trolley, Cineplex Odeon Trolley Square Theaters, Mann Cottonwood Mall Theaters, Mann 6 Plaza Theaters.

In perhaps a too obvious attempt to overcome his zany wise-guy screen image Michael Keaton takes a major dramatic plunge in "Clean and Sober," and the comparisons to Michael J. Fox in "Bright Lights, Big City" and Robert Downey Jr. in "Less Than Zero" are natural.All three actors are better known for light comedy than drama, and all three play cocaine addicts who come clean only with great difficulty. Each movie is a strong indictment of drug abuse, but then this is a subject that has built-in public sympathy.

Of these films, "Clean and Sober" seems the most successful. It is definitely the most harrowing, by far the best written and benefits greatly from a surprise knockout performance by Keaton.

But the question remains, does the moviegoing public really want to see another downbeat drama about the evils of alcohol and drug abuse?

That is for you to decide, but taken on its own, "Clean and Sober" is a fine film - "The Lost Weekend" of the '80s, perhaps.

We meet Keaton as the phone wakes him up one morning. He is in bed next to a woman he picked up the night before. After a night of doing drugs she has had a heart attack and can't come out of a drug-induced coma.

So Keaton hides his stash and phones the police.

Keaton's character is an abrasive, obnoxious commercial real estate salesman who has embezzled $90,000 from his company to keep his habit going. But neither this high-rolling theft nor the girl in his bed shakes him up enough to make him quit coke. He still needs a snort.

With the police on his case and the boss about to discover his embezzlement, Keaton decides to check into a drug clinic - not to quit his habit. Just to go into hiding.

There he meets tough-as-nails counselor Morgan Freeman, who doesn't take any of his guff and who knows every trick - the word an addict hates most to hear is "no," he explains; Alcoholics Anonymous sponsor M. Emmet Walsh, who tries to get Keaton to face up to his addiction and to face every problem head-on rather than trying to lie his way out; and fellow junkie Kathy Baker, with whom Keaton eventually falls in love, complicated by her long-term relationship with a surly ex-con.

These characters play pivotal roles in his life, and the actors all give fabulous performances. But there's no question that this is Keaton's film - he's in virtually every scene. And he doesn't let the script down.

There are many powerful, moving moments in this film, in particular when Keaton phones his parents to beg for money, when he tries to hide out at a friend's home and is turned away, and when he tears his office apart looking for some small envelope of powder to help him through the night. (The latter is very much like a famous scene in "Lost Weekend.")

In many of Keaton's other films you can imagine interchanging some of the characters he plays in that hip Bill Murray-Steve Guttenberg-Tom Hanks persona, such as those in "Mr. Mom" and "Night Shift."

But in "Clean and Sober" Keaton has a volatile edge that seems very real. He's dangerous - not just to himself, but to just about anyone around him. Keaton delivers a noteworthy performance and proves he has talent beyond what we might have expected.

"Clean and Sober" is sobering indeed, with a logical story that progresses believably and which, of course, has something to say - both to drug users and their loved ones.

It is also a tough film, rightly rated R for violence, profanity, sex, nudity, vulgarity and drug use.