There’s no lack of shoot-’em-up action in director Michael Mann’s Public Enemies: violent bank robberies, prison breaks, chases by car and on foot roar across the screen.

And there are stellar performances by Johnny Depp as 1930s bank robber John Dillinger and Academy Award-winner Marion Cotillard (for the Edith Piaf biography La Vie en Rose) as his girlfriend, Billie Frechette.

Yet despite all that, Public Enemies is surprisingly, disappointingly flat.

Mann spends so much time on the thrills that there’s little time left for background on Dillinger, who was America’s Most Wanted Man at the height of the Great Depression.

The always-interesting Depp gives a compelling performance, however, self-assured and a little cocky. In one of the film’s few humorous moments, he walks into a police station and wanders into the office of the “Dillinger Unit,” where the cops are glued to a baseball game on the radio, paying him little attention.

Depp’s Dillinger can be kind and sentimental one minute, striking in rage the next as when he hammers down a man who is impatiently waiting for his coat at a nightclub while the gangster is making time with the hat-check girl. It’s a startling, mercurial show and yet one of the problems with the script by Mann and Ronan Bennett is that one never gets far enough inside Dillinger’s head to discover exactly what made him the man he was.

When the film opens, Dillinger is at the center of a prison break as he is being returned to the Indiana State Penitentiary, after only eight weeks of freedom following his nine-year stretch there.

Depp’s scenes with Cotillard, who spent four months with a dialogue coach to replace her French accent with a Midwestern one (mostly successful), are vibrant. The two actors have a strong screen chemistry that makes their romance hum. And yet because we know so little about them beyond what we see on screen and because Billie is not present during key scenes in the film — Dillinger’s often hiding out or away working with his gang — they don’t have a chance to turn their relationship into a great romantic legend like the movies did for that other ’30s outside-the-law couple, Bonnie Parker and Clyde Barrow.

In advance of its release, the studio publicity machine was thumping the drums that Public Enemies would have a special appeal to today’s audiences, battered by a sinking economy and distrustful of banks, who would rally to bank-robber Dillinger. Advance word made Dillinger sound like a sort of Robin Hood.

But although there is a brief scene showing people on a sidewalk cheering him on as he’s taken to the lockup, what we see on screen is mostly Dillinger acting like a thug. (Despite the film’s plural title, there are only passing references to other gangsters of the era, such as Pretty Boy Floyd, although Baby Face Nelson does turn up late in the film as Dillinger’s trigger-happy partner in a bank robbery gone wrong.)

Mann, who won praise for such high-level gangster tales as Heat and Miami Vice, uses lots of close-ups and a very fluid camera that swirls around the characters. And yet one wishes for more medium or long shots to at least set the scene. It’s like being at a play and being plopped down on stage in the actors’ faces.

As much as the film is about Dillinger, however, it is nearly as much about his longtime nemesis Melvin Purvis (Christian Bale). A straight-arrow government agent, Purvis is dispatched by public relations-savvy J. Edgar Hoover (Billy Crudup) who hopes to use the resulting publicity of Dillinger’s capture to plump up the status of his FBI for which Hoover is still struggling to wring funds from a reluctant Congress.

Square-jawed, handsome, tight-lipped and determined, Purvis is hot on Dillinger’s trail though the gangster seems always one step ahead thanks to either luck or inept police work. Bale makes a confident but rather shadowy and grim figure that is even more inaccessible than Depp’s Dillinger. Bale and Depp have only the sparest of scenes together, a fact of history that gummed up the chance to make them true rivals.

Dillinger loved the movies, we’re told, which proved to be his undoing. Amusingly, at one show he’s startled to see his face flashed on screen in a newsreel segment about some of America’s most wanted criminals. In another, he attends a showing of the 1934 gangster film Manhattan Melodrama, starring Clark Gable, and Mann lets us see several key scenes from that movie. Maybe that was a mistake because Manhattan Melodrama seems more interesting than Public Enemies.

***Public Enemies

Starring: Johnny Depp, Marion Cotillard, Christian Bale, Billy Crudup, Peter Gerety.

Rated: R, contains violence, profanity, adult themes.

mjanuson@projo.com