Customarily, it is an unpromising sign when you do not know how to correctly punctuate a title, because it has so many different parts jangling about. My current operating guess is The Bad Lieutenant: Port of Call: New Orleans, which runs afoul of rules about serial colons, but then again, nobody - not even the film's director - claims that it's a particularly elegant or even functional title.

The title, however, is the only thing about the movie (that I will, to preserve my sanity, henceforth refer to as Port of Call: New Orleans) that's even a little bit bad. Everything else about it is damn awesome, which isn't something you get to just assume about any old Nicolas Cage vehicle, given his absurdly spotty track record, especially this decade; but you know who you do get to assume it of, is Werner Herzog, that insane German sprite who is one of the most important and original filmmakers now working, and whose career had started to look pretty much like he'd decided just to be a documentarian these past few years. Since the turn of the decade, his only narrative features have been Invincible and Rescue Dawn - both of them fine movies as such, but not really characteristic of a man whose rΓ©sumΓ© includes the like of Even Dwarfs Started Small and Fitzcarraldo, to name just two I picked at random. With stunningly idiosyncratic marvels like The White Diamond, Grizzly Man, and The Wild Blue Yonder making up his recent output it seemed at least possible that Herzog had put regular fictional storytelling behind him.

So if there's one thing that makes me flat-out love Port of Call: New Orleans, it's that the film is testament to the fact that the director still has it in him to make one of those extraordinary tales of demented men who push themselves to become even more demented over the course of the movie, as wot he used to do all the time with Klaus Kinski. And truly, who is closer to Kinski in these degraded times than Cage? - an actor who is probably not clinically insane, but certainly demonstrates only a tenuous connection to reality every time he opens his mouth onscreen or off.

Cage and Herzog click together better than just about any first-time actor & director combination in recent memory; better even than my most outlandish hopes (though hope does not customarily run very high when Cage is factor). In Herzog, Cage has found a director capable of harnessing his trademark breathy, jerky line delivery in the service of creating a character who starts out as dangerously unhinged and goes crazy from there; in Cage, Herzog has found a fearless actor willing to run into the psychotic depths of the scenario with both arms wide open. The result is Cage's best performance in many years, and perhaps ever: for never before has in indulged in such wild excess to such great effectiveness.

Opening in the aftermath of Hurricane Katrina, the first we meet of Sgt. Terence McDonagh (Cage) is as he and fellow New Orleans cop Stevie Pruit (Val Kilmer) stand in a flooding jail, taking bets on what time the single prisoner left trapped in his cell will finally drown in the rising water. Here we see McDonagh perform just about the only decent act of the film, as he reluctantly jumps into the stagnant, neck-deep water to save the poor bastard. For this action, he is promoted to lieutenant, and six months later he is given a plum assignment in recognition of his unusual gifts as a policeman: he is put in charge of a high-profile murder case, trying to determine who killed a family of five undocumented Senegalese immigrants - two of them children - in what bears the unmistakable marks of a drug-related execution. Unbeknown to his superiors, McDonagh knows a thing or two about New Orleans's drug world: he has quite the cocaine and crack habit going, aided and abetted by his well-to-do prostitute girlfriend Frankie (Eva Mendes). Nominally, the rest of the movie involves watching as McDonagh investigates and eventually cracks the case; practically, we're just hanging on and watching as a bad man descends further and further into a sleep-deprived, crank-fueled hell of his own devising. Every scene practically seems to take McDonagh past sensibility and coherence, and Cage pulls no punches in realising that arc.

The original draft of the screenplay took place in New York (like Abel Ferrara's 1992 Bad Lieutenant a film to which Herzog's film of William Finkelstein's screenplay owes essentially no debt whatever), but the transfer of the action to New Orleans in 2006 is essential what makes Port of Call: New Orleans work at all, let alone to the outstanding degree that it does. Perhaps it is little more than New Orleans exploitation, but all such exploitation should be this meaningful: as McDonagh fractures and becomes an ever-less functional human being, and as the corruption surrounding and sometimes involving becomes all the more vile and widespread, we are seeing nothing but a metaphor for the dissolution of society and order that resulted from the United States' abandonment of that city to its ruin in August, 2005. Port of Call: New Orleans is a story of wickedness within and wickedness without, and I can think of no better way to describe the facts of what happened in reality when, in the heart of the most advanced industrial nation in the world, a major city was stripped of the niceties of civilization for a little while.

Being a Herzog film, none of this is at all as serious as I've made it out to be; indeed, the film is a comedy before it is aught else. Not a silly, goofy "ha ha, these are gags" sort of comedy, of course. A miserable, terrifying, "ha ha, that man is a batshit loon that I can't take seriously" sort of comedy - it is full of the most nervous kind of laughter, but I do not use "full" advisedly - I haven't laughed so much at any movie since this summer's In the Loop.

The humor, which word I don't want to use but I can't think of one better, is built into the fabric of the movie not just from its plot and protagonist, but also from its staging and framing: as usual, Herzog finds a collection of the oddest angles to frame images (there are shots of a pair of iguanas, filmed by the director himself using cheap video, that are among the most original and giddy sights you will see in a theater this year), coupled with some unnervingly long takes focused on very little other than Cage's increasingly disturbed face. It is a potent movie, and one that takes a very particular kind of viewer to engage with the bed: if I say "Herzog is back", and you say, "Thank God", you are exactly the person to love Port of Call: New Orleans. If not, you should strive to become that kind of person, and Port of Call: New Orleans is a perfectly outstanding place to begin.