Leave it to Robert Zemeckis - relentless innovator and elite box-office showman - to turn a centuries-old Anglo-Saxon poem into the year's most gloriously entertaining action movie. Like the dragon felled by our computer-generated hero, “Beowulf” sweeps you up in its talons and gives you a harrowing ride.

Set in sixth-century Denmark, the movie employs the same motion-capture, not-quite-human visuals that distinguished Zemeckis' “The Polar Express.” It leaves the characters with a somewhat doll-like affect - as if they all had full-face Botox treatments - but finer emotions do occasionally break through, like the look of romantic desolation that crosses the face of Queen Wealthow (Robin Wright Penn) as her elderly husband, King Hrothgar (Anthony Hopkins), makes a sloppy drunk of himself at a rowdy celebratory feast.

Alas, there's something rotten in the state of Denmark, and that thing is Grendel, a shrieking, disfigured demon that bursts into the king's newly christened mead hall and starts feasting on his guests like cocktail wieners. Glimpsed in the eerie-blue light of a supernatural fire, Grendel makes for a fantastically terrifying monster; with his raw, exposed eardrums and melted-wax profile, he looks like the twisted progeny of H.R. Geiger and the Brothers Grimm. Properly mortified, the king sends out an APB for a hero.

Enter Beowulf (Ray Winstone from “Sexy Beast”), a golden he-man ferried onto shore by a small army of loyal thanes and an ego the size of Odin's rumpus room. If there's one thing Beowulf likes doing more than vanquishing sea monsters and the like, it's telling people about it, often - as his loyal right hand, Wiglaf (Brendan Gleeson), notes - with colorful embellishments.

Arrogantly stripping down to his bare Danish assets, Beowulf makes relatively quick work of Grendel (voiced, often unintelligibly, by Crispin Glover) and unwittingly draws the ire of the monster's bog-dwelling mother. And here is where “Beowulf” - scripted by celebrated graphic novelist Neil Gaiman (“Stardust”) and “Pulp Fiction” co-writer Roger Avary - departs, effectively, from tradition.

Beowulf doesn't exactly “slay” the mother, played as a slinky demonic temptress by a ravishingly computer-enhanced Angelina Jolie, but does realize his most vainglorious fantasies as a ruler. The decades pass, the guilt ferments and a fire-breathing embodiment of the hero's sins is unleashed on the land, resulting in the most lavishly thrilling medieval action sequence since “The Return of the King.”

Lest audiences mistake “Beowulf” for a “Shrek”-style family fantasy, let's disabuse anyone of that notion right here. Zemeckis has created a bawdy, irreverent epic, full of flatulence and off-color limericks. It has the visceral electricity of “300” with a superior human story. At select Imax and digital theaters, you will also find it in 3D. And what a jaw-dropping spectacle it is.

‘Beowulf'

Stars: Ray Winstone, Anthony Hopkins, Angelina Jolie

Behind the scenes: Directed by Robert Zemeckis, from a script by Neil Gaiman and Roger Avary

Rating: PG- 13 for intense sequences of violence including disturbing images, some sexual material and nudity

Running time: 1 hour, 41 minutes

Grade: A-