"Public Enemies" is an undernourished and perplexing crime drama, a film so indistinct in what it wants to do and say that it ends up doing and saying nothing at all. Those expecting a biopic of infamous bank robber John Dillinger or a meticulous historical recreation of the events leading up to his assassination in the summer of 1934 are best to look elsewhere. Likewise, those wanting to learn a little more about Dillinger and what made him tick will leave not knowing any more than they already did before the picture started. Surely the book on which it is based—Bryan Burrough's "Public Enemies: America's Greatest Crime Wave and the Birth of the FBI, 1933-34"—must be more informative than this slick exercise in emptiness. Writer-director Michael Mann (2006's "Miami Vice") and co-writers Ronan Bennett and Ann Biderman either have seen their intentions squandered in a whittling down of the final cut, or are working on autopilot.

Set within a one-year period that gives no background information or insight into its central human subject, John Dillinger (Johnny Depp) and several of his fellow cohorts/inmates break out of Indiana State Penitentiary and go on the run across the Midwest, picking up where they left off in their criminal careers as serial bank robbers. Hot on their trail is Chicago FBI chief Melvin Purvis (Christian Bale), who makes it his life's mission to apprehend or kill Dillinger, whichever comes first. Also entering the equation is Billie Frechette (Marion Cotillard), a middle-class beauty searching for adventure and finding it in Dillinger. When he tells her on the same night they meet that he robs banks, Billie doesn't let that deter her affections.

"Public Enemies" was shot by director Michael Mann and cinematographer Dante Spinotti (2008's "Flash of Genius") using the CineAlta F23 high-end HD camera, a shiny piece of equipment that increases facial clarity—every pore on the faces of Johnny Depp (2007's "Sweeney Todd: The Demon Barber of Fleet Street") and Christian Bale (2009's "Terminator: Salvation") are glimpsed in significant detail—but also appears underlit and captures distances as if they were filmed on a home-video camera. Individual images range from the vibrant to the murky, and it helps no one that the shots are always in motion, zooming this way and that and not lingering enough to even get a good look at the majority of characters. For an ensemble filled out with recognizable faces, most of them are so negligently recorded that one doesn't even notice who they are. Even would-be major figures, like Dillinger's right-hand men Charles Makley (Christian Stolte) and Homer Van Meter (Stephen Dorff), don't make any real impression. When, near the end, Dillinger spots a lineup of photographs of his mates, the word, "deceased," stamped on all of them, the moment holds no emotional weight because each of them has been so poorly developed as to barely be considered characters at all.

Deep narrative deficiencies plague the film. The story, opening while the plot seems to be in midstream, is vacant of complexity, so simplistic that it boils down to a bland 140-minute cat-and-mouse game. The robbery sequences are brief afterthoughts, and no attempt is made to explore the motives behind John Dillinger's actions or his relationships with his co-conspirators and sometimes-girlfriend Billie Frechette. Melvin Purvis' pursuit of Dillinger follows a predictable course, and, again, not an iota of detail is offered about who Melvin is. He's a vague sketch of a screenplay construct of a real-life human being. Furthermore, the film does not give us a reason to be on either side. Should we be rooting for Dillinger, even though he is a criminal and deserves to be locked up? Should we be behind Purvis, even though he needlessly shoots and murders his targets in cold blood? And what about Billie? Why is she so passively quick to stand by Dillinger even when he abandons her for long periods of time while he flees authorities and continues his crime spree? Their romance, like everything else, makes no sense because it is merely skimmed over in the screenplay with little interest paid to what they see in each other.

As the elusive John Dillinger, who in one admittedly amusing scene pays a visit to the Chicago Police Department's Dillinger investigation unit and goes undetected by the workers staring him right in the face, Johnny Depp is in full-on cool, suave, hotshot mode. Behind that sure-headed façade is no detectable depth, though; he might as well be playing the part of a blank canvas. As Purvis, Christian Bale is a little better than he was as the gruff, humorless John Connor in "Terminator: Salvation," but this has certainly not been his banner year as far as performances go. Bale is left untested and underworked. Marion Cotillard (2006's "A Good Year") brings a lively spark to Billie Frechette, but disappears for so long in the middle hour that one forgets she is in the movie at all. She does her best with a thankless role. The rest of the large cast are basically wasted in nothing parts, though Leelee Sobieski (2008's "88 Minutes") is so eye-catching as Polly Hamilton it is a shame she doesn't have more to do than walk arm-in-arm with Dillinger for a few scenes.

"Public Enemies" is a disappointment, a botched job that could have been the summer's best bet for adult audiences tired of giant robots and wanting a little more substance in their cinemagoing fare. Taking into account the talent involved in front of and behind the camera, the finished product is almost a travesty. With no ideas or themes to ponder, no characters to connect with, no texture or meat to its true-life stylings, no memorable dialogue, and no momentum or tension apparent until near the very end, the film is downright amazing in the ways it has gone wrong. Rare positives include art direction, production design and costumes that are seamless in their period flavor, and a handful of arty shots (one, taking place in a movie theater, is a wily reference to the famous moment in Alfred Hitchcock's "Strangers on a Train" set at a tennis match). The rest of "Public Enemies," alas, is coldly ineffectual bordering on transparent, so thin as to evaporate from the mind the moment it is over.