All the parts come together in 'Eclipse'

Her mouth says yes, I will marry the vampire.

But her heart says wait, let's not count the werewolf out.

In "Eclipse," the third film based on the popular supernatural romance books by Stephenie Meyer, poor Bella Swan could literally be torn between two lovers at any moment.

The first "Twilight," directed by indie filmmaker Catherine Hardwicke, set up a straightforward, low-budget romance between morose high school student Bella (Kristen Stewart) and her undead classmate, shimmering Edward Cullen (Robert Pattinson) with a sparkly set of golden peepers.

The sequel, "New Moon," directed by Chris Weitz, took a downer turn into soap operatic mush with lots of teen angst emanating from Bella, who wants to become a vampire, and from Edward, who at 109 years old really isn't a teen, and doesn't want to "bite" Bella until they are properly married. Who knew?

"Eclipse" comes from director David Slade, who gave us "Hard Candy," an edgy thriller about a tough little girl (a pre-"Juno" Ellen Page) who traps a pedophile and sets out to neuter him with kitchen utensils. Right away, you'd expect "Eclipse" to be shade darker and nastier than its predecessors. It is.

Slade never lets the inherent silliness of "Eclipse" stop him from throwing everything into this project, which is part epic, part teen romance, part war movie, part comedy and as violent as a PG-13 movie can probably get.

Bella has real trouble following through on her plan to spend an unhuman eternity with Edward. She keeps leading on poor Jake Black (Taylor Lautner), the shirtless hunk of lupine beefcake who wants her for himself when he's not in werewolf form.

In the movie's most grandiose plot twist, Jake and Edward's love for Bella causes the two sworn enemies to work together to protect Bella from an army of "newborns," freshly minted vampires under the control of the fiery-haired Victoria (Bryce Dallas Howard, replacing Rachelle Lefevre).

So many things can go so wrong in a movie like "Eclipse," yet Slade propels the narrative along through the slightly phony digitally rendered wolves (despite a bigger effects budget), clinker dialogue ("I don't want to lose you!" Bella says), Lautner's cringe-worthy line readings, and frequent posed group portraits of the wolf guys and glistening vampires suitable for the cover of GQ magazine.

Then there's the winter scene where Bella shivers in an unheated tent, and undead Edward can't use his cold body to warm her up. Shirtless Jake offers to bring the heat.

"Let's face it," Jake says to his rival. "I'm hotter than you!"

Apparently, werewolves have a gift for understatement.