The blood flows, “Swan Lake” plays on 78 rpm records and “tiny dancer” jokes abound in the revolting and funny “Abigail,” a “dead before dawn” thriller about a kid ballerina kidnap victim who turns out to be a vampire.

One and all mutter and even sometimes shout “WTF?” or the words that acronym stands for, and repeatedly, as that’s a natural human response to “What do we know about vampires?”

“That they aren’t real.”

Entirely too much of the tale is given away in the trailers, which causes this Matt Bettinelli-Olpin and Tyler Gillett film, scripted by Stephen Shields and Guy Busick, to lumber out of the gate and take a while to get going. And there’s a lot of momentum-killing “explaining” in the second and third acts that stops the gory fun in its pointe-shoes tracks.

But as little Alisha Weir jetes and pirouettes through a kidnappers’ hide-away mansion that has become “a trap,” a mansion supposed to be somewhere in New York state but which the six kidnappers (Melissa Barrera, Dan Stevens, Kathryn Newton, Kevin Durand, William Catlett and the late Angus Cloud) plainly race by the unique Samuel Beckett Bridge (in Dublin) in their getaway van to get to, one and all are reminded of the simple fact that there are few things on this Earth as terrifying as an entitled twelve year old girl.

And this one can’t be killed, or so it is said of the toothy undead.

We meet the kidnappers, “professionals” of varying degrees of professionalism, as they pull off the complicated kidnapping of a child, all alone in her mansion after she’s been deposited there by her chauffeur-driven Rolls after an evening of dancing “Swan Lake” in an empty and ornate opera house.

The man who hired them (Giancarlo Esposito) gives these “rats” “Reservoir Dogs” style nicknames — straight out of Sinatra’s “rat pack.”

There’s the “brains,” Frank (Stevens, just seen in the “Kong X Godzilla” movie), the blonde hacker Sammy (Newton, “Ant-Man’s” daughter, all grown up), the cluelessly hitting-on-the-women driver Dean (Cloud, of TV’s “Euphoria”), the dim-witted French Canadian muscle Peter (“Locke & Key” character actor Durand) and the sniper Rickles (Catlett of “Constellation”).

The only one with empathy has to be the ex-Army nurse, Joey (Melissa Barrera of the recent “Scream” reboot), in charge of sedating their quarry.

“It’s a 24 hour job,” Lambert (Esposito) reassures one and all. That $50 million ransom is as good as in the bag as “the hard part’s over.”

But we know it is. Oh yes we do. We’ve seen the trailers.

Referencing the Agatha Christie book originally titled “Ten Little Indians” is a cute inside joke, as all thrillers of this sort spin out of that killing-off-the-kidnapper/victims one by one, “And Then There Were None” formula.

The overarching joke is how this “tiny dancer” is such a monstrous, unstoppable killing machine. Kudos to Ms. Weir for getting across a personality in between the effects that give her oh-so-many teeth and cover her in gore. She’ll never be unemployed, from this day forward, so long as there are fan conventions where she can sign autographs and grin for selfies.

“I’m sorry about what’s about to happen to you.”

Stevens, the most oft-employed of the class of “Downton Abbey,” brings a snippy impatience to his “leader” role, with Durand grand at playing “dumb” muscle and the late Mr. Cloud rendering another version of an amusingly-dopey and tone-deaf stoner-villain.

Newton, Catlett and Esposito deliver what limited goods their characters are charged with carrying.

But Barrera, bringing back the ’70s shag haircut all by herself as “Joey” accidentally sets the horror in motion, and then tries to work-the-problem their way out of it, carries the picture. She is an arresting presence and a serious candidate for horror’s new “Scream Queen.”

Out of all the comical, panicked and despairingly serious “WTFs” delivered in this revolting romp, even after it stops romping, Barrera’s are the ones that make you go “indeed. What the eff can they do now?”

Rating: R, graphic violence, profanity

Cast: Kathryn Newton, Giancarlo Esposito, Alisha Weir, Kevin Durand, Melissa Barrera, Dan Stevens, Will Catlett, Matthew Goode and Angus Cloud.

Credits: Directed by Matt Bettinelli-Olpin and Tyler Gillett, scripted by Stephen Shields and Guy Busick. A Univeral release.

Running time: 1:49