Chalk it up to Americans’ overly anxious views of parenting, but here’s a phrase one tends not to hear in the States as the childrens’ bedroom lights are switched off: “If the wolves come out of the walls, it’s all over.”

Lucy, the nervous but resourceful young heroine at the center of the tingly musical “The Wolves in the Walls,” now being presented at the enterprising New Victory by the National Theatre of Scotland, is hardly comforted by this piece of advice, which she gets from both parents as well as from her big brother. Up until that moment, her drab house has been what she calls “rubbish for adventures,” but those nighttime visitors quickly put an end to that.

It should come as no surprise that the wolves do, in fact, make it out of the walls. After all, the selling points of the show are its source material (the acclaimed children’s book by Neil Gaiman and Dave McKean, which featured the fanged beasties prominently) and the involvement of Julian Crouch, who conjured up all sorts of macabre delights in the hit musical “Shockheaded Peter.”

What is surprising — and a bit unfortunate — is that this “musical pandemonium,” as it’s billed, ceases to be nearly as scary or interesting once the wolves do surface. What’s all over, it turns out, are those fresh-as-yesterday chills at the thought of the boogeyman stealing closer and closer to your childhood bed. In their place are a series of charming but innocuous images that may captivate youngsters but will likely leave grownup spines lamentably untingled.

Lucy (Helen Mallon) loves to draw, and the lupine invaders first appear in the form of her own primitivist chalk sketches — replications of the book’s eerie illustrations by Messrs. Gaiman and McKean. But the other family members get their own forms of release, too. Dad (George Drennan) bleats a woozy cadence on his tuba, Mom (Anita Vettesse) drums away at her numerous jars of jam, and Brother (Paul James Corrigan) shows off his video-game skills with rock-star aplomb. (The creators miss an opportunity here, depicting mushrooms-and-baddies games of the Super Mario vintage as opposed to the newer, more apropos breed of Guitar Hero and Rock Band music stimulations.)

Co-conceivers Vicky Featherstone (who also directed), Nick Powell (whose original score casts a respectful nod to the bleepy bloopy fun house dissonances of film composer Danny Elfman), and Mr. Crouch (who designed the sets and costumes) contrast these pedestrian activities with the harrowing imaginings that confront Lucy and her beloved pig doll every night. First Lucy — and the audience — merely hear the wolves, a guttural sort of wail; soon disembodied eyes and then full silhouettes appear, in the form of Mr. Crouch’s legitimately creepy animations and shadow puppets.

Soon, the family is forced to flee as the wolves take over. (Lucy inadvertently leaves her doll behind, leading to one of the more poignant images, that of a stuffed pig struggling up a staircase to safety.) A menacing, vacant-eyed, easily diverted batch reminiscent of the velociraptors in “Jurassic Park,” the critters quickly make themselves comfortable. Dancing a tango with a vacuum cleaner, breaking into a loose-shouldered hiphop dance, giggling over self-inflicted electric shocks, they wreak havoc until Lucy rallies her parents and brother into recapturing the family manse.

A hard-working quartet of puppeteers employ two different methods: Sometimes they content themselves with wearing elaborate wolf masks and walking upright, as with the vacuum tango, but usually a gangly full-body version drapes over their bodies, piggyback-style. In either case, the wolves are as endearing as they are malevolent: When a disguised Lucy diverts them by breaking into a Charleston dance, they happily join along for a while before nipping at her jitterbugging ankles.

In a bedtime pronouncement only slightly less dubious than their comment on the wolves, the parents sing to Lucy, “Now it’s time for everything to end.” Any kid with an overheated imagination — that is to say, every kid — knows that the creatures of the night, be they Wild Things or wolves, wait until that liminal, lonely time to start up.

Until October 21 (209 W. 42nd St., between Broadway and Eighth Avenue, 646-223-3010).