One might think that having taken three years to deliver a sequel to 2015’s effects-heavy family movie that makers of “Goosebumps 2” could have come up with something more than a virtual carbon copy of its predecessor. Of course, maybe that’s all the kids who enjoyed the original will want.

Like the first movie, the follow-up is based on the world of R.L. Stine’s “Goosebumps” books but not directly adapted from any one of them. The 2015 picture took off from the idea that the various creatures Stine had devised could be released into the world if the manuscripts of the books were unlocked—which of course they were, leaving the malevolent ventriloquist’s dummy Slappy to lead all the others in an effort to take over the world.

This time around, the catalyst of mayhem is a book Stine supposedly never finished, titled “Haunted Halloween.” The manuscript is found, locked up along with Slappy, in a decaying old mansion in Wardenclyffe, New York, once owned by Stine. The discoverers are a couple of middle-school kids, Sonny Quinn (Jeremy Ray Taylor) and his pal Sam Carter (Caleel Harris), who’ve been hired to clean out the place. They take book and dummy home, and before long Slappy has been reanimated and is causing all sorts of trouble, bringing to life all the ghoulish stuff locals have put out to celebrate Halloween, and more besides.

The key to Slappy’s scheme is to start up the unfinished tower built by Nikola Tesla in Wardenclyffe way back in 1901 (but still in spic-and-span condition), using the power it generates to take his plan worldwide. (Slappy’s not the only one fascinated by the gizmo: Sonny has also built a habitually malfunctioning model of it as a school science project.) By the time this closing segment kicks in, Jack Black has again shown up, unbilled this time, as Stine, encouraging the kids to write the final chapter of the book he was never able to complete.

That ties in with another plot thread, in which Sonny’s older sister Sarah (Madison Iseman) is struggling with writer’s block writing her college admission application; now she’ll be able to finish it without difficulty, since she’s joined forces with her brother to defeat Slappy and done what Stine hadn’t. (Along the way Slappy, who—in another of the movie’s messages—only wants a family of his own, takes revenge on the caddish classmate who broke Sarah’s heart by taking up with another girl.) There’s also Tommy (Peyton Wich), an obligatory bully who targets Sonny and Sam and gets his comeuppance; but he’s a PG-friendly bully who, when he chases the boys on his bicycle, takes care to put on his helmet first. Don’t ride without yours, viewers!

The kids are alright in “Goosebumps 2”—not particularly good actors, to be sure, but about on the level of the youngsters you’d find in a live-action sitcom on the Disney Channel or Nickelodeon. The adults don’t fare so well. The characters are all clueless, of course, but the unlucky actors taking them on do a particularly bad job with them. As the Quinn children’s mother Kathy, Wendi McLendon-Covey mugs brutally, though she comes across as restrained compared to Ken Jeong, who does his usual grotesque shtick as their holiday-crazed neighbor. Then there’s Chris Parnell, as a drug store clerk infatuated with Kathy whom Slappy transforms into his Igor-like assistant. Of them all, he’s probably the one who suffers the greatest embarrassment, although he goes through much of the movie under heavy makeup.

But the human performers, young or old (including Black and Stine himself, who returns for a Stan Lee-like cameo), are of minor importance beside the army of special-effects critters that overwhelm the movie, just as they did its predecessor. Sony Pictures Animation does a pretty decent job with them, although none show much personality except for Slappy, whom Black again voices in a whiny intonation that’s not enough to make up for his lousy puns and bad jokes. Otherwise the movie looks like a made-for-cable kids’ movie, with production designer Rusty Smith and cinematographer Barry Peterson giving everything a chintzy, soundstage feel.

“Goosebumps 2” might pass muster as inoffensive eye-candy for the pre-teen set, but it certainly doesn’t improve on its mediocre predecessor, or bode well for any future installments.