Then again, Terence McDonagh (Cage) may be more of a snake skimming the murk, like the water moccasin navigating the rising tide in the film's unsettlingly beautiful opening shot.
Not so much inspired as ignited by an eccentric script from television writer William J. Finkelstein, Herzog creates an atmosphere sticky with amorality. For the filmmakers, New Orleans is a delirium state where all bad deeds go unpunished and vice versa.
The film spins with McDonagh's whirling moral compass. As the waters rise in the Katrina prologue, McDonagh dives into a lockdown to set free a drowning prisoner.
His reward for this act of kindness? A promotion and a back injury that gets him addicted to Vicodin. In a pinch, he'll use any prescription or street drug that can stanch the pain. And there are a lot of pinches.
McDonagh routinely shakes down suspects for drugs. And if the suspects don't have them, there's always the property room at the precinct or the stash of his prostitute girlfriend, Frankie (Eva Mendes), whose johns McDonagh loves to mess with. And did I mention that he is a sports gambler who owes thousands to his bookie?
Physically and morally compromised, McDonagh lurches through town, getting himself deeper and deeper into drugs, gambling, debt, and danger.
Herzog (Grizzly Man), a courageous explorer of the thin evolutionary line between man and beast, sees McDonagh as a cold-blooded guy who thinks only with his reptilian, i.e., primitive brain.
In keeping with that metaphor, when McDonagh is coked-up, he hallucinates Gila monsters on the coffee table, one of the many surreally funny images in this seriocomedic nocturne.
With his scaly skin and darting movements, Cage is demonic, clinging to professional responsibilities while behaving most unprofessionally. As the Bad Lieutenant spirals down into hell, his spirit dances to police-procedural rhythms only he can hear. It's ridiculously entertaining.
When Cage is good, he is very, very good, but when he is bad, he is better.
Contact movie critic Carrie Rickey at 215-854-5402 or email@example.com. Read her blog, "Flickgrrl," at http://www.philly.com/philly/blogs/flickgrrl.