Filled with unexpected turns and subversive humor, Werner Herzog's Bad Lieutenant: Port of Call New Orleans is a jazzy, entertaining riff on the theme of a cop who spends too much time in a sewer of criminality and corruption.

It's a far cry from Abel Ferrara's 1992 NC-17 film with a similar title, and it will appeal to a different audience. It has a seriously involved performance from Nicolas Cage as a good detective on a downward spiral of drugs and gambling; there is a lot of very black humor; and it develops, somewhat surprisingly, into something suggesting a kind of cheerful pessimism. Herzog has made a piece of mainstream entertainment with quirky particulars, and with Cage's star power, it could see substantial rewards from the domestic and international box office. (First Look Pictures releases it stateside.) The film was greeted at the Venice festival, where it's a competition entry, with much laughter and, at the end, loud, sustained applause.

Veteran TV cop show writer William Finkelstein's screenplay sets the story in New Orleans in the aftermath of Hurricane Katrina, and it allows Herzog to explore the way bad things happen to good people while crooked people prosper.

Cage plays dedicated police officer Terence McDonaugh, who in the opening sequence jumps into a flooded basement cell to save a locked-up prisoner from drowning, permanently injuring his back. Prescribed medicines ease the chronic pain that he is left with, but soon he's taking illegal drugs, whatever he can find or steal.

The framework of the picture is a police procedural with McDonaugh and his colleagues, including Steve (Val Kilmer), on the trail of the killers of a family of five caught up in drug dealing.

All the while, McDonaugh is trying to score whatever will make the pain go away, and there are many inventive, scary and sometimes hilarious scenes showing how he goes about it. He has a hooker junkie girlfriend (Eva Mendes) and a tolerant bookie (Brad Dourif), and he runs afoul of powerful bad guys while playing ball with a significantly dangerous drug lord.

Kilmer doesn't get to do much, but Mendes and Dourif make fine contributions, as do Fairuza Balk as an amorous former flame and Alvin Xzibit Joiner as the drug king. But it's Cage's show, and his body language conveys just how much pain McDonaugh is in, with one shoulder permanently clenched and his gaze on alert for the next fix. It's a sly, intelligent performance that brings to mind the tortured character he portrayed 20 years ago in the grievously overlooked Vampire's Kiss.

Ferrara's Bad Lieutenant was a lurid depiction of a very damaged detective made memorable by a committed performance by Harvey Keitel. That cop's drug-induced illusions involved a lot of Catholic guilt and visions of Christ. Herzog mischievously has the cop in his film see lizards. Iguanas and alligators pop up when least expected, and there's a funny scene in which the camera captures an iguana up close, with Cage's demented cop in the frame looking weirdly related.