Johnny Depp's charisma and matinee idol looks aren't reason enough to fall in love with Public Enemies, Michael Mann's saga about Depression-era bank robber John Dillinger. Depp is magnetic, but not that magnetic. For all its surface beauty and energetic gunplay, this underwritten picture doesn't cut very deep and is rather unmoving. It's as though the mere idea of a film about a popular outlaw portrayed by an appealing actor will suffice.

Mann, whose filmography includes The Insider, Heat, Collateral, and Miami Vice is an impressionistic director -- a skilled creator of moods whose best efforts are more akin to musical compositions than works of narrative fiction. The problem with Public Enemies is that there's only one mood or feeling and little progression.

The guiding notion appears to be that American moviegoers are preternaturally inclined to romanticize criminals. Public Enemies harkens back to the 1930s and '40s -- the heyday of Jimmy Cagney, George Raft, Edward G. Robinson and Humphrey Bogart -- when Hollywood was enamored of gangster films. The implication is that nowadays we need reminding of how compelling lawbreaking heroes can be. Whether or not that's true, given the financial meltdown and criminal behavior of so many establishment figures on Wall Street and Main Street (and the failure of government and law enforcement to do anything about it), the time may be ripe for celluloid crooks with a Robin-Hood philosophy.

But Mann and co-writers Roman Bennett and Ann Biderman, basing their script on the book by Bryan Burrough, don't make a convincing case that a chivalrous hood who gives his topcoat to a female hostage, let's a customer keep his money (he only wants the bank's), and is at bottom just a regular Midwestern farm boy is really worth our time and attention. We don't learn enough about what made Dillinger special apart from the outer trappings. His own taste for gangster pictures is too circular to carry much weight.

The straightforward plot begins with Dillinger busting his pals out of the Indiana State Penitentiary in 1933 and takes us up to his death in front of Chicago's Biograph Theater approximately one year later. An FBI team led by Special Agent Melvin Purvis (Christian Bale) is close on his tail most of that time, during which he meets and woos coat-check girl Billie Frechette, played by Oscar-winner Marion Cotillard. There are a handful of tense, well-staged scenes (you suspect Tommy Guns were invented to Mann could film them) and the sets, art direction and cinematography are first-rate. Missing however is the dread and menace Mann found on the streets of L.A. in Collateral for instance. And while a pivotal shootout in the Wisconsin forest has immediacy, nothing in Public Enemies comes close to the visceral power of the long confrontation between bank-robbers and cops he staged in downtown L.A. in Heat.

Mann is a master at contrasting light and dark, noise and silence, especially during scene transitions. Yet without the dramatic layering to match, it amounts to style over substance. Attempts to probe Dillinger's psychological make-up aren't what's needed, unless they might give us more reason to care about what happens to him and his associates. The bond between Dillinger and Billie isn't as ironclad or captivating as the film assumes. An angle that could have been pursued further is how organized crime figures stopped supporting Dillinger because they deemed the attention his smash-and-grab jobs attracted were bad for their more sophisticated lines of crime.

Public Enemies seems to go out of its way to belittle the nascent FBI and its leader J. Edgar Hoover (Billy Crudup) -- to the extent that the plural title refers to the G-Men as much as it does to Dillinger and his kind. With the exception of Purvis and an agent excellently portrayed by Stephen Lang, the bureau is depicted as being manned by corrupt, cruel incompetents. Bale's stolid aura contrasts well with Depp's star persona in theory, but in practice the movie leaves you wanting something in between stone-faced and pretty boy.

Depp brings a dashing bonhomie and sense of humor to the role yet ultimately the performance comes off as too lightweight to carry the movie far enough. Mann takes a big risk showing so many snippets of Manhattan Melodrama, the film about a doomed and noble hood Dillinger was transfixed by the night he died. You exit the theater after seeing Public Enemies with the nagging feeling that if it were Clark Gable playing Dillinger, you'd care a lot more. Depp-lust and technical fluency isn't enough to anchor this gangster film or render it a meaningful homage to the genre.

(Released by Universal Pictures and rated "R" for strong violence and some language.)