Twenty years after finishing up his planned zombie trilogy—1968's "Night of the Living Dead," 1979's "Dawn of the Dead," and 1985's "Day of the Dead"—writer-director George A. Romero returns with a vengeance to the undead genre that he arguably created with the brooding, Grand Guignol bloodbath "Land of the Dead." The fourth picture in what could now be labeled a quadrilogy, "Land of the Dead" suffers when juggling its one-dimensional characters, but gets just right the horrific aspect of what it might be like to live in a world overrun by the living dead. Coincidentally, however, 2004's Romeroless "Dawn of the Dead" remake—an improvement over the dated, long-winded original, to boot—is a step above what "Land of the Dead" has to offer, both from a fright and emotional standpoint. In comparison, this latest film is like a really good appetizer, satisfying while it lasts but not amounting to as much as one hopes.

Picking up several years after the events of "Day of the Dead," the living population has been safely relegated to blocked off and barricaded areas where they have been forced into two groups: the wealthy and illustrious, who, in the fictional city that "Land of the Dead" takes place, reside in the grand, multipurpose Fiddler's Green skyrise, and everyone else, who remain homeless and must fend for themselves. Meanwhile, the long since risen undead have taken over the rest of the town, gradually evolving enough to almost carry on kinda-sorta lives of their own. Nonetheless, they still have an insatiable hunger for human flesh and blood, which poses a definite problem when they begin making their way across the river that separates the dead from the living.

When discussing the basic setup and premise of "Land of the Dead," it is unnecessary to even mention the slimly developed human characters, who fulfill their requirements but aren't given a chance to come into their own as people worth caring deeply about. Cholo (John Leguizamo) diligently answers to the every whim of snide Kaufman (Dennis Hopper), owner of Fiddler's Green, hoping that his hard work will win him a spot in the building. When Kaufman makes it clear that this isn't going to happen, Cholo decides to steal the giant, rambling Dead Reckoning bus of steel. The hero of the piece is Riley (Simon Baker), who is given an offer by Kaufman to bring Dead Reckoning back to him, but he has other plans of his own. With the living dead circling ever closer to their turf, Riley, along with best friend Charlie (Robert Joy), a friendly burn victim, and tough-as-nails ex-hooker Slack (Asia Argento), plan to take the bus for themselves and head north to anticipated safety.

That is about all that the viewer learns about the people onscreen, but then, "Land of the Dead" isn't about character development so much as it is about getting to the cannibalistic, stomach-churning gore. Still, it wouldn't have hurt had Romero paid more attention to his cast, all proven to be top-notch actors; the "Dawn of the Dead" redux did create more fully rounded figures, and was all the better for it because their unavoidably grim fates meant something to the audience. "Land of the Dead" doesn't hold such close scrutiny, and ends on an anticlimactic note that seems to be missing a third act. Just as the action and horror appear to be taking off, the movie just ends, and rather disappointingly.

Before this letdown of a finale, "Land of the Dead" does exactly what it sets out to do, complete with vivid, fear-drenched atmosphere and superb make-up and special effects, so bloody and graphic that they nearly drip off the screen. One thing filmmaker George A. Romero is a master of is making his undead villains fully memorable, from the intelligent head baddie Big Daddy (Eugene Clark), to the cleaver-wielding Butcher (Boyd Banks) to the mouth-decaying teenage softball player Number Nine (Jennifer Baxter). Romero does such a good job conveying these creatures that they are arguably a whole lot more interesting than the protagonists.

In the twenty years since Romero's last foray into the series, he has also improved visually and cathartically as a horror film artist. The jump scares are unforced and actually work, the nighttime cinematography by Miroslaw Baszak is gorgeously foreboding, helped by some fine use of locations in Toronto (posing as an American city), and the pacing is tight and never stops moving. Certain images are particularly indelible, with the opening shot of a town now operated by the dead its most haunting and unshakable, almost approached in effectiveness by another sequence in which hundreds of the zombies rise out of the waters they have just learned how to cross.

Gritty, dark and unapologetically violent, "Land of the Dead" is a solid, serious zombie movie that wisely leaves most of its tongue-in-cheek humor in the hands of a standout performance by Dennis Hopper (1999's "EdTV"), who is at his slimy best as the pompous Kaufman, who inevitably gets his just desserts by the end. For 80 minutes or so, "Land of the Dead" actually seemed to be headed in the direction of being George A. Romero's best film since his groundbreaking "Night of the Living Dead," made all the more intriguing by its political and socioeconomic undercurrents that view the undead as just another form of being trying to make their way in the world. Regrettably, this promise of greatness is not fulfilled by the end credits, which come at an inopportune time when the climax seems to have only just begun. There is a missed opportunity in what "Land of the Dead" strives for, and yet, it will undoubtedly please those fans of Romero's who have been waiting two decades for another "Dead" installment. Until he gets a chance to strengthen his ideas and craft in a hoped-for fifth film, the adroit, gruesomely fun, but ultimately underwhelming "Land of the Dead" will have to do, and, more often than not, it does.