The good news about the “Underworld” series, in which a mangy army of werewolves presses a millennium-spanning blood feud against their heretofore vampire slave masters, is that there’s not a hell of a lot that could be done to ruin it. Len Wiseman, who puked out the first installments like two fat hunks of greasy blue cheese, now hands the saber for the third, a prequel, over to his creature designer.

If anyone deserves a “break” like this one, it’s Patrick Tatopoulos. He’s paid his dues in the credit roll’s third act for years, and his resume reads like the map of a movie geek’s heart.  He’s been working in and around the art and special effects departments of some of the most respected crappy movies made in the last 20 years. “Pitch Black,” “Resident Evil,” “I, Robot,” “I Am Legend,” even the recently buried, much sought after Halloween anthology “Trick ’R Treat” all bear the mark of his design and effects work. He’s done zombies, aliens, robots, serial killers, video game characters, serial killing video game characters ... he even designed Emerich’s “Godzilla” for cryin’ out loud. The man knows monsters.

There may not have been a better possible choice to lens a B-level bodice-ripper about a rebellious vampire warrior princess seduced by an angry (yet sexily articulate) werewolf slave as he brews violent rebellion amongst his hairy brethren against her iron-fisted 1,000-year-old dad. Trading out the steamy underground decay of contemporary subways and sewers from the first two for the steamy underground decay of ancient castle dungeons, Tatopoulus does maybe too good of a job mimicking Wiseman’s tepid visual style. Just as his predecessor, he drowns every frame with swaths of unnatural blue light, and chops rapidly between competently composed mid shots to jarring extreme close-ups. Though discarding most of the original’s boorish vampire committee politicizing in favor of excessive scar-crossed romantic melodrama and tooth and nail action sequences, the copious fight scenes seem conspicuously engineered to mask either a lack of choreographic budget or the fighting skills of the cast.

Which brings us to the cast.

Michael Sheen appears to be having the time of his life as the bad boy alpha dog, though that just might be a testament to his skills as an actor. The slight, thin-lipped, boyish little thesp has a notably reputable track record. He’s played Tony Blair no less than twice—first in Stephen Frears’ “The Deal” in 2003, and in 2006’s “The Queen.” He’s also gained some recent attention headlining in Ron Howard’s Oscar-bait intellifest “Frost/Nixon.” For better or worse, in all three “Underworld” pictures he shows a gnashing, bug-eyed enthusiasm. He strains his chains, and shakes his cage and flexes his weasely body like a summer stock JC Superstar. His considerable history in live theater has given him an impressive set of pipes, too, and he snaps and snarls and barks out even the most overwritten, undercooked lines with a stagely gusto. He simmers with the best of ’em, but seeing such a lemur of a man attempt this level of superstar posturing, one can’t help be reminded of skinny Michael Keaton when he first turned up in the rubber Batman fetish gear.

Then we’ve got Bill Nighy, returning as a more centrally figured vampire overlord, Viktor. Nighy is famously known as the “you’re not my dad” from “Shawn of the Dead.” He makes a fabulous aristocratic dandy in any case, but especially in movies like these. Though rocking a perfectly Bowie Brititude, he manages to render even the most slimy and villainous roles into exasperated straight-men, even when corsetted up to his jowls in buttons, buckles and brocade. As the vamperor, he lets his Bunsen blue contacts and black velvet “battle-skirt” do almost as much of his acting for him as he did with Davy Jones’ tentacle beard in the “Pirates of the Caribbean” flicks. More power to him. Name another sextagenarian who can gnaw the marrow out of lines like “Fetch my knives” in a velvet skirt like he can. Didn’t think so.

Series newcomer Rhona Mitra has no fear of B-movies either. Her contributions to high concept vehicles like “Doomsday” and “Skin Walkers” will not soon be forgotten. The relish she throws on these baloney sandwiches is the stuff of legend. She bites right into her role as the heaving chested, pointy toothed heroine, thundering around on horseback often with a sword in one hand and a dog-soldier throat in the other.

And speaking of dog-soldiers, let’s not neglect Kevin Grevioux, the low-rent Michael Clarke Duncan-looking shapeshifter with the voice (and body) of an oak tree. A scientist by training, writer by nature and an actor by accident, he actually contributed heavily to all three scripts, and has made a tasteful D-list living by ensuring his character is never written well or deeply enough to attract a name star like, say, Michael Clarke Duncan, to steal the role out from under himself. In addition to being perfectly believable as a creature one step away from the Discovery (or SciFi) channel, he’s got a specific type of “Get Shorty” genius you just don’t see every day.

It should come as no surprise that the “werewolf versus vampire” picture is ridiculous and outlandish and gives “nonessential” a whole new thesaurus entry. But if you’re a movie geek with a taste for blue cheese, you’ll chew it up. If you’re the Cineaste type who prefers the “reputable” movies, be sorry you missed “Let the Right One In.” Go buy a book about Murnau.