DON JUAN DEMARCO': DEFT, DAFT DEPP

In "Don Juan DeMarco," Johnny Depp gives another of the oddball performances that are making him the most charismatically eccentric actor of his generation. After playing a boy with scissor hands, a lost soul obsessed with silent comedians and a cross-dressing schlock filmmaker, Depp has proved that he can make us believe him in anything. This time, he slips into an impossible role -- a young New York man who may be the legendary 17th-century Spanish lover -- with his usual effortless conviction.

But then, there's only so much an actor can do. Written and directed by novelist-turned- filmmaker Jeremy Leven, "Don Juan DeMarco" turns out to be only occasionally amusing. The picture takes off when Don Juan, dressed in the great lover's full regalia -- mask, cape, sword and all -- indulges himself with one final conquest, then climbs atop a billboard, determined to end his life. Enter Dr. Mickler (Marlon Brando), who talks him down and installs him in a mental hospital.

This bristling first act opens up a world of intriguing possibilities and, early on, the movie looks as if it might ascend to the giddy heights of the fantastic. The scenes in which Don Juan, who immediately sends the female members of the staff into an erotomanic tizzy, engages Mickler in a debate over whether he's the doctor's patient or a guest at his "villa" are sharply written.

As the picture moves along, though, the emphasis shifts away from Don Juan to Dr. Mickler, and the flashes of inspiration all but disappear. When Mickler meets the alleged maestro of love, he is only 10 days away from retirement. Once a brilliant clinician, Mickler has lost his zest for living and for his wife, Marilyn (Faye Dunaway). As a result of Don Juan's challenges to his "limited view of reality," Mickler begins to question his assumptions about romance and growing old. "Where is the celestial fire that used to light our way," he asks his puzzled wife, who responds by saying that she'd take a nice steady glow over a raging bonfire any day.

Naturally, the old doc isn't satisfied. This kid -- either really Don Juan or merely John DeMarco from Queens -- has gotten under his skin. Though his superior at the clinic insists that he stop messing around with the boy and "put him on meds," Mickler isn't so sure. "How do you know he's not Don Juan?" he growls back.

Leven does have a point to make here -- even if it is rather specious and unoriginal. Mickler does know that his patient can't be Don Juan, but he begins to wonder what difference it makes. The kid is happier in his delusional world than most people are in their real lives; though medication might "cure" him, it would also destroy him.

Fortunately, Leven does not peddle this theme as a genuine revelation; instead, he keeps the film's tone light and ingratiating. And, though the material is thin, the actors do seem to be getting a kick out of playing off each other.

This is especially true of Brando, who does, for once, seem to enjoy being in front of the camera. This is not to say that Brando is actually good in the role; here the sublimely instinctive actor is playing a character that in no way taps his gifts. It's fun to see him having fun, but he's still acting with one hand tied behind his back. Dunaway has her moments too, though she suffers more from the constrictions of the script than her co-stars do.

It is Depp who manages to transcend the picture's flimsy premise. In many ways, he's much like the young Brando, though his talents may be even more puzzling and harder to classify. Part chameleon, part magician, Depp puts the mystery back in acting.

Don Juan DeMarco, at area theaters, is rated PG-13.